Abstract: Substituted XML Semi-Structured Data Files System for the traditional database based on common B/S mode, and designed an E-Commerce System Model based on DAS (Data As a Service), which mainly included Client Data Encryption、Server Key Management and the query processing of XML enciphered data by data service provider etc.The query processing of XML enciphered data in user orders are implemented by XML index technology combined with Dewey coding.It is shown that, on the premise of security and stability, the proposed solution can greatly reduce the maintenance cost of system, and improve its performance and operation efficiency, which is beneficial to promote the enterprise benefit.