CAR T cells have shown promise in treating hematological cancers but face significant challenges in solid tumors. This review outlines the obstacles and strategies to enhance CAR T cell therapy in solid tumors. Solid tumors present unique challenges, including the identification of specific antigens, spatial localization of tumor cells, and survival in hostile microenvironments. CAR T cells must navigate these barriers to effectively target and destroy cancer cells. CAR T cells are engineered to express chimeric antigen receptors (CARs) that recognize tumor antigens. These receptors consist of an extracellular domain for antigen binding and intracellular domains for signaling. Early generations of CARs lacked co-stimulatory elements, limiting their efficacy. Subsequent generations incorporated co-stimulatory domains, improving persistence and activation. Fourth-generation CARs, such as TRUCKs, produce cytokines to modulate the tumor microenvironment. Antigen selection is critical for CAR T cell therapy. While antigens like CD19 are effective in liquid tumors, solid tumors often lack specific, highly expressed antigens. Tumor antigens may be heterogeneous or expressed in normal tissues, leading to off-target effects. Strategies to enhance specificity include dual CARs, TanCARs, iCARs, and SynNotch technology, which allow for multiple target recognition and reduced tumor escape. The tumor microenvironment (TME) poses significant challenges. It can suppress CAR T cell activity through immunosuppressive signals, physical barriers, and metabolic conditions. Strategies to overcome these include co-stimulatory molecules, remote-controlled CARs, and fourth-generation CARs that secrete cytokines. Additionally, targeting immune checkpoints like PD-1 and CTLA-4 can enhance CAR T cell efficacy. Despite these advancements, CAR T cell therapy remains limited by high costs, manufacturing complexity, and the need for more effective strategies. Ongoing research aims to improve specificity, reduce toxicity, and enhance the ability of CAR T cells to infiltrate and persist in solid tumors. These efforts are crucial for expanding the application of CAR T cell therapy to a broader range of cancers.CAR T cells have shown promise in treating hematological cancers but face significant challenges in solid tumors. This review outlines the obstacles and strategies to enhance CAR T cell therapy in solid tumors. Solid tumors present unique challenges, including the identification of specific antigens, spatial localization of tumor cells, and survival in hostile microenvironments. CAR T cells must navigate these barriers to effectively target and destroy cancer cells. CAR T cells are engineered to express chimeric antigen receptors (CARs) that recognize tumor antigens. These receptors consist of an extracellular domain for antigen binding and intracellular domains for signaling. Early generations of CARs lacked co-stimulatory elements, limiting their efficacy. Subsequent generations incorporated co-stimulatory domains, improving persistence and activation. Fourth-generation CARs, such as TRUCKs, produce cytokines to modulate the tumor microenvironment. Antigen selection is critical for CAR T cell therapy. While antigens like CD19 are effective in liquid tumors, solid tumors often lack specific, highly expressed antigens. Tumor antigens may be heterogeneous or expressed in normal tissues, leading to off-target effects. Strategies to enhance specificity include dual CARs, TanCARs, iCARs, and SynNotch technology, which allow for multiple target recognition and reduced tumor escape. The tumor microenvironment (TME) poses significant challenges. It can suppress CAR T cell activity through immunosuppressive signals, physical barriers, and metabolic conditions. Strategies to overcome these include co-stimulatory molecules, remote-controlled CARs, and fourth-generation CARs that secrete cytokines. Additionally, targeting immune checkpoints like PD-1 and CTLA-4 can enhance CAR T cell efficacy. Despite these advancements, CAR T cell therapy remains limited by high costs, manufacturing complexity, and the need for more effective strategies. Ongoing research aims to improve specificity, reduce toxicity, and enhance the ability of CAR T cells to infiltrate and persist in solid tumors. These efforts are crucial for expanding the application of CAR T cell therapy to a broader range of cancers.