Abstract: The effective way of reducing memory accessing delay of the multi-core multi-thread processor is to design L2 Cache reasonable.This paper aims at the present multi-core multi-thread processor, then discusses the design project of mixed-prefetch structure of L2 Cache.By particular design and simulation analyses，it indicates that mixed-prefetch structure can improve the performance of processor remarkably.Furthermore, mixed-prefetch structure with prefetch under miss strategy suits the multi-core multi-thread processor much better，which meets the requirement of the multi-core multi-thread processor with this structure.