Abstract: Objective To investigate the effects of sinomenine on analgesia and contents of substance P in central nervous system of incisional pain rat model. Methods Sprague-Dawley rats were randomly divided into model group, lornoxicam group (8mg•Kg-1), sinomenine high-dose group (20mg•Kg-1) and sinomenine low-dose group (10mg•Kg-1). The tests of mechanical allodynia and heat allodynia were used to evaluate the pain behavior of the rats. The contents of substance P were measured by RIA. Results The mechanical and heat pain sensitive behaviors of incisional pain rats changed significantly. After administration, sinomenine high-dose group and lornoxicam group had the effects on analgesia, and sinomenine high-dose was fond of lornoxicam group. Compared with the contents of substance P in cerebrospinal fluid and spinal cord of model group, sinomenine high-dose group, sinomenine low-dose group and lornoxicam group were all decreased significantly (P <0.05). Conclusion Sinomenine can relieve the pain sensitive behavior of incisional pain rats. Its analgesic effect may be related to inhibiting releasing of substance P in central nervous system.