A shader auto-simplifying method and system include: obtaining a rendering instruction flow, extracting a target shader from the rendering instruction flow, and creating a simplifying shader differing from the target shader in code only; intercepting a current frame of a rendering instruction with a rendering initiating instruction of the target shader as a particular frame; obtaining time consumed by the simplifying shader by measuring time needed for rendering the particular frame with the simplifying shader; obtaining error(s) of the simplifying shader by measuring a pixel difference value between a rendering frame drawn by the simplifying shader and the particular frame when a rendering instruction corresponding to the particular frame is executed; and screening an optimal simplifying shader according to the time consumed by the simplifying shader and the error of the simplifying shader.