The invention provides a VR fitness interaction system based on unity 3D. A sport information collecting module is used for collecting bicycle sport speed and angle information, a virtual scene generating module is used for generating a scene simulating an actual fitness scene, external equipment is used for displaying a virtual scene and capturing moving information of a user, and a VR interaction module is used for the user to interact with objects in the virtual scene. By means of the system, VR fitness scene diversification is achieved, diversified scenes are created by using developing tools, specific scenes are created according to demands, the system has lower hardware cost, the demand that current VR sport equipment must be deeply customized is not needed, the system is assembled by using a normal bicycle and the external equipment, a general solving scheme is provided, the cost is greatly reduced, the system has interactivity and interestingness, a virtual reality technology is combined, the user can immerse in diversified virtual scenes by wearing a helmet when the user does fitness exercises, which is like being in a real outdoor environment.