Mobile Client Cache can improve the performance of the mobile database system.However,it leads to the problem that data in server and in cache are not consistent,that is,cache inconsistency problem.People often maintain the cache coherency through the cache invalidation algorithms based on broadcasts.Conventional cache invalidation algorithms based on synchronous broadcasts or asynchronous broadcasts have both advantages and disadvantages.The paper discusses the conventional algorithms and some existing algorithms and puts forward an improved adaptive cache invalidation algorithm based on counters,it integrates the two conventional algorithms,and it can improve the cache utilization rate and reduce the communication overheads.