Abstract: Objective:To locate the anal injury by continuous anorectal manometry. Methods: The pressures and periods of the radial 8 channels manometry in the anus were compared on an experimental model of 10 dogs pre- and post-operatively. The statistics was carried out by student's t test. Results: The resting and squeezing pressures and their periods had not statistical significance preoperatively, but they decreased postoperatively. The resting and squeezing pressure of channel 3 decreased comparing with channel 7, the squeezing period prolonged, the resting period had not statistical significance. Conclusions: The anorectal manometry is a reliable method to locate the anal injury.