The invention provides a cloud rendering system based on software definition. The system comprises an application layer, a control layer, an infrastructure layer and a data layer. According to the method, a rendering software resource control method is reconstructed, a corresponding function model is established, and a custom instruction system is provided and comprises an analysis instruction, ajudgment instruction, a resource scheduling instruction, an execution instruction and a communication instruction; and according to the software definition characteristics, the rendering process and the management process are modified, so that the method is more flexible. According to the cloud rendering system, centralization, control and execution are separated, the rendering resources, the access mode, the deployment mode and the implementation function of the rendering resources are decoupled and reconstructed, the functions of the system are optimized while the centralized resources are enhanced, the overall load is reduced, and the system can operate more efficiently and extensively; and the user can set the 3D rendering engine, the plug-in required to be used, the rendering server scale, the rendering cluster management software and the customized rendering environment by himself / herself, and the cost is controllable, so that the requirements of different users in various rendering scenes are met.