Objective Most men suffering from depression have different degrees of erectile dysfunction (ED), but the relationship between depression and ED is not clear. This study explored the effect of depression on erectile function in rats and the underlying mechanism. Methods The potential targets and key signaling pathways of depression and ED were predicted through bioinformatics analysis, and a depression rat model was established by inducing chronic restraint stress. Pathological changes in rat penis tissue were studied by hematoxylin and eosin staining. The serum dopamine level was quantified by an enzyme-linked immunosorbent assay. The expression of related proteins and mRNA was detected by western blotting and real-time quantitative reverse transcription-polymerase chain reaction. Results Hematoxylin and eosin staining showed pathological damage in the penile tissue of the model group rats. The serum dopamine level, dopamine receptor D2 (DRD2) and solute carrier family 6 member 3 (SLC6A3) protein levels in penile tissue, and DRD2 and SLC6A3 mRNA levels were lower in the model group than in the control group. Conclusion The decrease in erectile function in the depression rat model was related to dysfunction of the dopamine system and dopaminergic synapse signaling pathway.