With the development of e-commerce, security has been the center of the transaction. This article analyses the technologies of e-commerce and then examines the issues related to the security of assets and transactions in the e-commerce components and activities. After examining the technologies used in e-commerce, the article goes on to identify the security requirement of ecommerce systems from perceived threats and vulnerabilities. Then e-commerce security is viewed as an engineering management problem. And a life cycle approach is put forward.