Chloroplasts are crucial for photosynthesis and various biochemical processes in plants, and they are highly sensitive to salt stress. Salt stress affects chloroplast structure, photosynthetic processes, osmotic balance, and reactive oxygen species (ROS) homeostasis. Plants have developed various mechanisms to cope with salt-induced toxicity on chloroplasts, ensuring their normal function. The salt tolerance mechanism is complex and varies among plant species, so many aspects of these mechanisms are not entirely clear. This review explores the effects of salinity on chloroplast structure and function, and discusses the adaptive mechanisms by which chloroplasts respond to salt stress. Understanding the sensitivity and responses of chloroplasts to salt stress is essential for understanding the role of chloroplasts in plant salt stress adaptation and for enhancing plant salt tolerance. Salt stress causes osmotic stress, ionic stress, and oxidative stress to chloroplasts. The initial osmotic stress leads to stomatal closure, which affects carbon fixation in photosynthesis by limiting CO₂ supply. Excess accumulation of Na⁺ and Cl⁻ ions inside chloroplasts disrupts ion homeostasis and inhibits the uptake of K⁺ and Ca²⁺ ions. Additionally, the decline of carbon assimilation and reduced photosynthetic electron transport rate increases ROS production, leading to oxidative stress. Thus, salt stress negatively affects chloroplast structure and function. Chloroplasts have evolved sophisticated mechanisms to acclimate to salt stress. For example, the xanthophyll cycle dissipates excess excitation energy in PSII, and ascorbate and water-water cycle protect photosynthetic machinery from oxidative damage. Chloroplasts possess candidate Na⁺, K⁺, Cl⁻ ion transporters that can regulate ion concentrations, but the ion transport capacity differs between salt-tolerant and salt-sensitive plants. In response to osmotic stress, plant cells uptake inorganic ions from the external environment and produce organic osmolytes such as sorbitol, mannitol, proline, glycine betaine, and polyamines, most of which are localized in the chloroplast. Chloroplasts are major ROS production sites, and salinity increases ROS accumulation, causing oxidative stress. Certain enzymatic and non-enzymatic antioxidants are present in chloroplasts to scavenge ROS. Chloroplasts are sensitive to salt stress, which affects chloroplast size, number, lamellar organization, starch accumulation, and so on. Under normal conditions, chloroplasts have ellipsoidal shapes with regularly organized grana stacks and dense stromal thylakoid lamellae. Salt stress causes chloroplasts to deform into irregular shapes with reduced grana stacks. Excessive salinity also leads to thylakoid swelling in the chloroplasts of Thellungiella salsuginea, primarily caused by disruption of chloroplast osmotic equilibrium. Thus, high salinity changes chloroplast shapes and lamellar organization. Salt stressChloroplasts are crucial for photosynthesis and various biochemical processes in plants, and they are highly sensitive to salt stress. Salt stress affects chloroplast structure, photosynthetic processes, osmotic balance, and reactive oxygen species (ROS) homeostasis. Plants have developed various mechanisms to cope with salt-induced toxicity on chloroplasts, ensuring their normal function. The salt tolerance mechanism is complex and varies among plant species, so many aspects of these mechanisms are not entirely clear. This review explores the effects of salinity on chloroplast structure and function, and discusses the adaptive mechanisms by which chloroplasts respond to salt stress. Understanding the sensitivity and responses of chloroplasts to salt stress is essential for understanding the role of chloroplasts in plant salt stress adaptation and for enhancing plant salt tolerance. Salt stress causes osmotic stress, ionic stress, and oxidative stress to chloroplasts. The initial osmotic stress leads to stomatal closure, which affects carbon fixation in photosynthesis by limiting CO₂ supply. Excess accumulation of Na⁺ and Cl⁻ ions inside chloroplasts disrupts ion homeostasis and inhibits the uptake of K⁺ and Ca²⁺ ions. Additionally, the decline of carbon assimilation and reduced photosynthetic electron transport rate increases ROS production, leading to oxidative stress. Thus, salt stress negatively affects chloroplast structure and function. Chloroplasts have evolved sophisticated mechanisms to acclimate to salt stress. For example, the xanthophyll cycle dissipates excess excitation energy in PSII, and ascorbate and water-water cycle protect photosynthetic machinery from oxidative damage. Chloroplasts possess candidate Na⁺, K⁺, Cl⁻ ion transporters that can regulate ion concentrations, but the ion transport capacity differs between salt-tolerant and salt-sensitive plants. In response to osmotic stress, plant cells uptake inorganic ions from the external environment and produce organic osmolytes such as sorbitol, mannitol, proline, glycine betaine, and polyamines, most of which are localized in the chloroplast. Chloroplasts are major ROS production sites, and salinity increases ROS accumulation, causing oxidative stress. Certain enzymatic and non-enzymatic antioxidants are present in chloroplasts to scavenge ROS. Chloroplasts are sensitive to salt stress, which affects chloroplast size, number, lamellar organization, starch accumulation, and so on. Under normal conditions, chloroplasts have ellipsoidal shapes with regularly organized grana stacks and dense stromal thylakoid lamellae. Salt stress causes chloroplasts to deform into irregular shapes with reduced grana stacks. Excessive salinity also leads to thylakoid swelling in the chloroplasts of Thellungiella salsuginea, primarily caused by disruption of chloroplast osmotic equilibrium. Thus, high salinity changes chloroplast shapes and lamellar organization. Salt stress