Objective:To study the therapy of abdominal cavity lukewarm water filling on the effect of biomechanical properties, such as tensile strength of rat rectal healing area after low rectal cutting-anastomosis, and to analyse further the constitution equation and viscoelasticity properties of rat rectum, in order to provide scientific basis for clinical therapy. Methods: There were 32 SD rats of the clean grade. At first performed the low rectal cuttinganastomosis, and then divided into control groupA of sinple cutting-anastomosis without filling and group B of abdominal cavity lukewarm water filling. Biomechanical experiments were done 5 days and 15 days after operation. Results: The tensile strength, elasticity modulus of increasing quantity and viscoelasticity of group B were significantly better than control group A, (P<0.05). Conclusion: By using the therapy of abdominal cavity lukewarm water filling, the biomechanical properties of rectal tissue after low anastomosis of rectal cancer was not only without any notable adverse effect, but also helpful to the improvement of rectal tissue biomechanical properties.