An embodiment of the invention discloses a method and a device for optimizing a kernel function and relates to the technical field of computers. By the aid of the method and the device, access time is shortened, and the performance of the kernel function is improved. The method provided by the embodiment comprises steps: determining reusable memory access space corresponding to a global memory access statement in a source kernel function, and loading reusable data in the reusable memory access space into shared memory to generate a first target kernel function.