An OLAP system for an electronic commerce system comprises an enterprise server, an OLAP server and a client, wherein the enterprise server, the OLAP server and the client become a three-layer structure of the OLAP system, and the OLAP system also comprises a basic database and a data warehouse, wherein the enterprise server, the OLAP server and the client are connected with the data warehouse; The application logic, GUI and DBMS are strictly separated in the three-tier architecture. Complex application logic is not distributed on the client, but centralized on the analysis server, which provides efficient data access and analysis preprocessing. The combination of WEB and OLAP can save the cost of development, directly using WEB Browser does not need to develop special software, and cross-platform, easy to promote, conducive to the enterprise from the centralized environment to the distributed open environment transformation.