Objective To study dynamic characteristics of the ankle gait simulator, simulate plantar forces in the vertical, anterior-posterior, right-left direction during the stance phase, and validate such forces in the experimental setup. Methods The Adams virtual prototype and ankle model (including tendons, ligaments and soft tissues of foot) were established for dynamic simulation based on the self-developed 5 DOF gait simulator. The dynamic results from both the prototype and gait simulator were compared with the real plantar forces. Results The simulated plantar force could accurately fit the normal in vivo ankle position curves during a stance phase in three directions, and the tendons, ligaments and soft tissues had important influences on the correct gait. The simulated plantar force by the gait simulator could be repeatedly fit for the real stance plantar force. Conclusions The gait simulator was proved to simulate the human gait stance well and can provide a clinical research platform for those experiments which are incapable of in vivo measurement.