Nowadays, with the appearance of more and more web services, it has been one of the key points that how to find the target service quickly and precisely. Traditional methods of web service discovery are only based on the keyword matching, but it's very difficult to realize more detailed and intelligent services, and the results are hardly to meet the user's demands. According to the current OWL-S, WSMO and other frameworks, a new lightweight semantic extension framework for web services is proposed in this paper, which is founded on the syntax structure of XML and the 3-layer frame of OWL-S, which can be compatible with the current web service and UDDI. If there is a need for semantic and intelligent search, one could use this framework to extend the web services by connecting the domain ontology. At last, the paper also provides a similarity matching algorithm for the corresponding layer. By integrating the 3-layer's algorithms, the user can achieve the expecting factor, and then choose a proper web service according to the expecting factor.