Abstract: Client semantic caching is a caching scheme based on semantic locality among client issued queries in client/server database system. Semantic cache is composed of former query results and corresponding descriptions. The LWI（least weight item）cache replacement policy for semantic cache considers the characteristic of semantic cache. The LWI replacement policy sets up a weight for each cache item, based on the access frequency of its projected attributes and the match results between queries and cache predicate, and also on the consideration of temporal locality concern. LWI replacement policy replaces the least weight item in the cache. Performance analysis results show that LWI replacement policy outperforms the traditional LRU and LFU cache replacement policy in semantic cache.