The bipedal humanoid robot WABIAN-2R is developed to simulate human locomotion. Performing a walking motion requires a high torque at the ankle joint. WABIAN-2R consists of harmonic gears in its driveline system which increases the weight of each leg and respectively decreases the energy economy. However, using a spring mechanism instead of high gear ratio transmission could decrease the energy used during walking motion. Therefore, the idea of installing the dynamic walking techniques to WABIAN-2R is proposed. Using computer simulation the design of the ankle joint is modified by adding a spring mechanism and controlled by twisting the joint to set the required torque. Based of dynamic simulation an important step toward developing the passive dynamics walking into the advanced complex humanoid robots is been purposed.