The invention discloses an online three-dimensional rendering technology and system based on a cloud platform, the system comprises a WEB front-end system, the WEB front-end system comprises an accesslayer and a front-end UI, and the access layer comprises a mobile phone and a PC terminal. A communication layer, a service layer and a data layer, a model subtraction optimization algorithm is adopted to carry out lightweight processing on a model file; a step of compressing a lightweight model after surface reduction optimization and a step of optimizing a model file through a real-time communication protocol are included. In addition, a parallel algorithm and a dynamic computing power rendering algorithm of a rendering pipeline are adopted to carry out lightweight processing on the model file; a user can obtain high-quality 3D rendering on any lightweight terminal; according to the online three-dimensional rendering system of the cloud platform, a product in a design is rendered and generated in the cloud server, designers from various countries or various regions can design in the same platform and directly communicate with each other to see a law and make a conclusion, and the modified design is verified together.