Keyframe overloaded technology was proposed in order to solve the problem that it was not realistic when virtual human based on keyframe system walked on the stairs. The differences and similarity of the models between virtual human’s ground walking and stairs walking were analyzed. Through a combination of inverse kinematics and keyframe animation, certain keyframes were redrawed to make the virtual human have a real-time response to the environment. The experimental results show that the method can be used to effectively improve the fidelity of the virtual walking.