Abstract: The production and development of spacecraft payload products are characterized by many kinds, multiple batches and small batches. In order to improve the software flexibility of automatic test system for payload products to cope with the challenge of increasing test project complexity. This paper proposes a software architecture of a test system based on dynamic link library technology, which has the functions of thread management,instrument resource management and test sequence editing. The software functions of user management, operation logic and instrument control in automatic test system are realized through the association design of three layer dynamic link library, and the detailed design scheme of each module in the system architecture is introduced in detail. Finally, the function of the system is verified by product testing. The test system based on dynamic link library technology proposed in this article has smaller program granularity and good expansibility. Through the flexible configuration and reconstruction of the three layer dynamic link library modules, the overall function of the test system software has been continuously upgraded, which greatly meets the requirements of the integrated test system for the production and development of the current space payload products and provide a new idea for the architecture design of the spacecraft test system.