Web services, with an emphasis on open standards and flexibility, can provide benefits over existing capital markets integration practices. However, Web services must first meet certain technical requirements including performance, security and so on. SOAP, based on Extensible Markup Language (XML), inherits not only the advantages of XML, but its relatively poor performance. This makes SOAP a poor choice for many high-performance applications. Cache is effective approach for improving the round-trip time for request-response exchanges. At present, there are lots of researches on server side cache implementation for Web Services have been presented, however, each of these studies has its own limitations and no one is the best in all situations. Focusing on these issues, this paper proposed a novel adaptive cache mechanism, which can choose an optimized cache implementation dynamically in the runtime. Moreover, this paper presented a fine-grained cache approach to obtain the further performance gain and design a cache key associated method to decrease the usage of memory. Through our experiments in this paper, we observed that our approach obtained a huge performance gain by incorporating the adaptive cache mechanism into the SOAP engine.