This article explores the design mechanisms and mechanical properties of various tough hydrogels and their applications in tissue engineering, flexible electronics, and other fields. Hydrogels, known for their high biocompatibility, are often limited by their network structure, which hinders their ability to possess a diverse range of superior mechanical properties. The authors discuss several strategies to enhance the toughness of hydrogels, including the introduction of sacrificial bonds, hierarchical architectures, network topology, and force-triggered length release. These methods aim to improve the strength, stretchability, toughness, and fast recovery of hydrogels. The article also highlights the potential applications of these tough hydrogels in tissue engineering, such as in bone repair, cartilage repair, and cardiovascular tissue regeneration, as well as in flexible electronics, including wearable sensors and bioadhesive materials. The review provides insights into the fabrication and application of hydrogels with combined high strength, stretchability, toughness, and fast recovery, while also discussing future development directions and challenges.This article explores the design mechanisms and mechanical properties of various tough hydrogels and their applications in tissue engineering, flexible electronics, and other fields. Hydrogels, known for their high biocompatibility, are often limited by their network structure, which hinders their ability to possess a diverse range of superior mechanical properties. The authors discuss several strategies to enhance the toughness of hydrogels, including the introduction of sacrificial bonds, hierarchical architectures, network topology, and force-triggered length release. These methods aim to improve the strength, stretchability, toughness, and fast recovery of hydrogels. The article also highlights the potential applications of these tough hydrogels in tissue engineering, such as in bone repair, cartilage repair, and cardiovascular tissue regeneration, as well as in flexible electronics, including wearable sensors and bioadhesive materials. The review provides insights into the fabrication and application of hydrogels with combined high strength, stretchability, toughness, and fast recovery, while also discussing future development directions and challenges.