Abstract: The shared L2 Cache optimization is extremely important in multi-core architecture, because the cost that L2 miss led to takes hundreds of cycles to access main memory is quite large.The replacement algorithm is an important factor considered for designing Cache and directly affects the performance of Cache and computers overall performance.Although the LRU replacement algorithm has been widely used in on-chip Cache, but there are also several deficiencies: When Cache size is smaller than program working set, it is easy to lead to conflict miss;LRU Replacement Algorithm not consider the access frequency.Bubble replacement algorithm in this article is applied to multi-core shared Cache;meanwhile take the recent access information and the frequency information of the data block into consideration.By analyzing the experimental data, compared with the LRU replacement algorithm, MPKI and the hit rate of L2 has been improved.