Objective Construction of an immune-tumor dual humanized mouse model to explore the role of targeting monoamine oxidase A ( MAOA ) in the immune microenvironment of prostate cancer. Methods Bioinformatics analysis was used to examine the relationship between MAOA^high cancer associated fibroblasts(CAFs) and T cells in prostate cancer. Multiplex immunofluorescence was employed to analyze the relationship between stromal MAOA expression and CD8⁺T cells. An immune-tumor dual humanized mouse model was constructed for in vivo verification of the infiltration of CD8⁺ T cells in response to the targeting of stromal MAOA. Results MAOA expression in the stroma was inversely proportional to the infiltration of CD8⁺ T cells. Inhibiting MAOA expression in the stroma enhanced the infiltration of CD8⁺ T cells in vivo, which may reflect suppression of the accumulation of collagen in the tumor microenvironment. Conclusions Stromal MAOA plays an important role in the immunosuppressive microenvironment of prostate cancer, and its inhibition may promote the infiltration of immune cells. MAOA inhibitors have therapeutic potential in immune combination therapy for patients with prostate cancer.