With the continuous growth of business volume and functional requirements, applications of major business systems are gradually upgrading from the Spring Boot architecture to the SpringCloud micro-service architecture. Due to the significant version change, internal testing and external joint testing need to be conducted sufficiently before the applications officially go online. Under the constraints of limited machine resources in the DMZ domain and minimizing the exposure to the public network of the existing joint environment, this paper proposes a dual-architecture application paralleling and flow switching scheme based on the Nginx-F5, which provides the test system with both the external joint testing functions of Boot and Cloud architecture applications. The scheme splits the requests of external merchants according to attributes such as merchant code, business type, or province code and a certain percentage and forwards them to the micro-service application system. In this way, the application in the micro-service version can be fully tested, which provides a reference for system expansion and construction that needs large version parallel testing.