The present invention provides an image accelerator and an image processing method. The image accelerator includes: a DMA controller, a buffer, a creater, and a composing slice element operation component. The DMA controller transfers the corresponding data stored in an external memory to the buffer; the creater takes data out from the buffer, conducts value inserting according to parameters, produces information of every point of a triangle, makes calculation on data of every pixel which is gotten after the value inserting, the composing slice element operation component conducts composing slice element operation on the parameter according to the signal of the creater, and writes results back to the buffer. The present invention does not excessively occupy the resource of the microprocessor and the accessing bandwidth of the memory, can meet the real time performance of the 3D image processing, can meet the requirement of the low power consumption of the equipment, and has low cost.