In order to improve the immersive experience of traditional animation design, an interactive animation design scheme based on virtual reality technology is proposed. This paper analyzes the construction of virtual scene of 3D animation, and studies the fusion technology of human and nature in virtual scene, focusing on the collection of human body surface data, the extraction of skeletal data and the fusion of virtual and real scenes; Based on Unity3D software, 3D animation design practice of human and nature fusion interaction is carried out, and the interaction between human arm and fireball is taken as an example to show the fusion and interaction control of human to fireball in virtual scene. The results show that the design has a certain reference value for the 3D animation design of human-computer interaction.