In　this　paper,　aiming　at　overcoming　the　shortcomings　of　traditional　RSJ　(Reduce　Side　Join)　algorithm　based　on　MapReduce　framework　model,　an　optimized　algorithm　is　proposed　to　increase　the　efficiency　of　the　RSJ　by　using　DistributeCache.　The　idea　of　Bit-map　algorithm　is　adopted　in　this　algorithm.　Specifically,　it　extracts　and　compresses　the　connection　attributes　of　one　of　the　tables　to　make　a　＂background＂　data　before　executing　the　traditional　RSJ　algorithm.　The　algorithm　uses　DistributeCache　to　spread　it　to　various　nodes.　The　＂background＂　data　is　able　to　filter　out　the　information　which　is　independent　from　the　records　in　the　table,　therefore　both　the　network　comnmnication　and　computation　cost　are　decreased,　which　increases　the　efficiency　of　RSJ.