The biped robot has the better mobility than the conventional wheeled robot. Since a biped robot tends to tip over easily, it is necessary to take stability into account when determining a walking pattern. To ensure the dynamic stability of the biped robot, we have to adapt the ground conditions with a foot motion and maintain motion, and ensure its stability through the kinematics and dynamics analysis. But its mathematic model is not too easy. In this paper, in order to ensure the dynamic stability of a biped robot, we design the fuzzy model and confirm the realization possibility of the proposed method through some simulations