In e-commerce environment, trading partners exchange product information in the form of e-catalogs. With the rapid developing of e-commerce and the increasing in the number of goods online, the e-catalogs accordingly become very large. As the result of the catalog in massive sites, not only customers are dazzling, but also business services are affected. At the same time, the main electronic catalog enquiring service-based on keywords also exist the problems that customers can not enquiry similar semantic and the related semantic goods and many other issues. For the customers, it is difficult to simply use keywords to faithfully express their real needs of goods. These issues make customers can not quickly and accurately gain results, and also reduce the company's management efficiency and profit-effective from the massive electronic catalog of product website.Electronic catalog contains rich semantics associated with products, and serves as a challenging domain for ontology application. Ontology is concerned with the nature and relations of being. It can play a crucial role in e-commerce as a formalization of e-Catalogs. In this paper, we present an ontological model of e-Catalogs, and design a semantic querying system based on e-catalog ontology (SQSEO).