Aimed at rapidly building simulation systems, service oriented simulation development is put forward, based on ontology and web service mechanism to custom and compose simulation services. First, some basic definitions, simulation services customization model were proposed and its supporting system framework were presented, among which domain ontology, requirement ontology and service ontology were particularly described. Logical relationship between requirement goals and simulation services were analyzed, upon which the general process of service composition were studied. In the end, with the support of Grid Toolkit a prototype system was realized to testify the feasibility of our methods.