In order to make the expression and action of animated virtual characters more realistic, this paper proposes a virtual character expression and action system based on 3D animation. The system hardware module is used to complete the collection and processing of image data and human bone data. Then, the positioning of human skeleton points and the mapping relationship between joint points and moving skeleton points are constructed, and finally the virtual character model is constructed. On this basis, this paper completes the correspondence of feature points through facial feature point mapping and completes the face model alignment by aligning the video face with the 3D animation virtual face. The Laplace coordinate recovery model is used to reconstruct the facial expression action, complete the simulation of 3D animation virtual character expression action and realize the design of the virtual character expression action system based on 3D animation. The experimental results show that in the aspect of expression movement, the system in this paper has a better effect than the real-time motion capture technology system and the 2D animation expression movement system with a 95.40% simulation degree. The fidelity of skin texture processing in this system is 97.60%. Conclusion. The designed system can effectively simulate the facial expression in the character image and integrate it into the three-dimensional animation to make the virtual character more vivid. After rendering and skin texture processing on the Unity3D platform of the system, the authenticity of the virtual character is enhanced.