This paper discusses the validation of a simulation model of biomechanical legs with passive toe-joints using Matlab/Simscape. The structure of the biomechanical legs was presented using Simulink tools. Each leg consists of seven revolute joints (six active joints and one passive joint) connecting the torso, thigh, shank, back-foot, and front-foot. The structure of the toe-joint was discussed and a novel model representation for the joint was demonstrated. To validate the simulation model, the ground reaction forces were modeled and the location of the Zero Moment Point (ZMP) under the foot was found using two methods; ZMP-based model and the ZMP measured from the ground reaction force. The results from both methods were compared for a simple gait to validate the dynamic model.