The present disclosure discloses a multi-stream image processing method that includes steps outlined below. Image streams that include a main image stream and at least one sub image stream are generated by a former stage circuit, wherein a resolution of the main image stream is higher than the resolution of the sub image stream. Within an image frame processing time period, a N-th sub image frame is stored in a current sub image storage block in a memory module and a N-th main image frame is stored in a current main image storage block in the memory module by the former stage circuit. Within a first sub period of the image frame processing time period, a N−1-th sub image frame is read from a former sub image storage block in the memory module by a latter stage circuit to perform processing. Within a second sub period of the image frame processing time period, the N-th main image frame is read by the latter stage circuit to perform processing.