The invention provides a communication system, a cache server and a cache content pushing and finding method and system. The cache server establishes a balance tree and a dictionary tree according to the type of a cache pushing request and judges the type of the received cache pushing request, a matched tree node is found according to the balance tree when the type is a regular expression type, a matched tree node is found according to the dictionary tree when the type is a relative path type, and after the matched node is found, the cache content corresponding to the node is updated. The cache content is flexibly stored and found in different modes according to the type of a pushing rule of the cache pushing request, the complexity of time for finding is low, and accuracy is high.