Abstract: To explore the ameliorative effect of Chlamys nobilis and its enzymatic hydrolysates on male sexual function, we investigated the sexual behaviors, organ coefficient, level of serum sex hormone, NO contents and enzyme activity of NOS in penile tissue of the hemi-castrated male SD rats. The results show that C. nobilis and its enzymatic hydrolysates could increase the sexual behaviors of hemi-castrated male rats, such as catching frequency (P<0.05) and mount frequency (P<0.05); decrease the errection latency significantly (P<0.01); and increase the coefficients of testicular and prostate-seminal gland in hemi-castrated male rats significantly (P<0.05). Besides, it could increase the serum testosterone content, stable the levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH). Moreover, it could mediate the production of NO and NOS in penile tissue significantly (P<0.05). Therefore, C. nobilis and its enzymatic hydrolysates can improve the reproductive capacity of hemi-castrated male rats, and the improvement mechanism is probably related to the regulation of serum sex hormones and the promotion of signal factors of penile tissue in hemi-castrated male rats.