Objective To investigate the analgesic effect of geniposide and its underlying mechanisms. Methods The analgesic effect of geniposide was studied by the hot-plate test and the acetic acid-induced writhing test. Through the naloxone antagonistic experiment and pretreated with nitric oxide donor L-arginine (L-Arg) and nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester (L-NAME) and then the contents of nitric oxide (NO) were measured to discuss the relationship of opioid receptors and NO to the analgesic effect of geniposide. Results Geniposide (12.5, 25, 50 mg/kg) showed a dose-dependent reduction of acetic acid-induced writhing counts and a significant improvement of pain threshold in hot plate test in mice(P<0.05). The analgesic effect of geniposide was partly antagonized by naloxone and L-Arg, but enhanced by L-NAME. Geniposide significantly reduced the contents of NO in serum and brain tissue of model animals (P<0.05). Conclusions Geniposide has strong analgesic effect, and the analgesic effect is related to activating opium receptor and suppressing the synthesis or releases of excessive NO.