To obtain a service composition approach that satisfies the multiple requirements of users and can be easily realized, a novel method based on events is proposed in this paper. Firstly, a simple event language for services is introduced, which can be regarded as a language based on ECA (event-condition-action) rule. Secondly, a composite scheme that describes the composite services is constructed with the modularizing method based on the rule language. The scheme can not only solve the representation problem of services composition domain when adopting AI planning (artificial intelligent planning), but also the insufficiency problem in description capability when the technologies such as UML (unified modeling language) are adopted. Thirdly, to effectively present the composite scheme, the paper accomplishes the scheme’s semantics definition and codes the scheme with answer set programs. Finally, the ASP (answer set programming) technology is utilized to present the composite trajectory.