Objective To investigate biomechanical characteristics of the modified memory alloy internal fixator for separation of pubic symphysis. Methods The model of pubic symphysis separation injury was established based on 10 pelvic specimens. The control group was fixed with the dynamic compression plate after reduction, and the experimental group was fixed with the modified memory alloy internal fixator for separation of pubic symphysis after reduction. The biomechanical stability for two kinds of internal fixation was compared. Results There were no loosening and fracture of internal fixation in both groups. The displacement of pubic symphysis in horizontal, anterio-posterior and vertical direction in the experimental group was obviously reduced compared with the control group (P＜0.05). Conclusions Compared with the dynamic compression plate, the modified memory alloy internal fixator for separation of pubic symphysis shows better resistance to the tensile force against horizontal and anterio-posterior direction, as well as better resistance to the vertical shear force.