Cloud computing is getting increased attention of the information and communication technologies. The cloud service providers the more multiplex, elasticity, and saves the cost the service resources. There are more and more mass security attack occurred in the recent years. Web security in the cloud system enhancement has become a very hot topic. Therefore this research introduces the security testing flow and provides a test approach tool which attempts to build up a secured cloud system base-line for every web project in Chunghwa Telecom-Lab, based on the black-box and system combinational testing technology for development department.