GB/T 3681.1-2021 is the general part of the standard for solar radiation exposure test methods for plastics. It lays the foundation for evaluating the performance changes of plastics under solar radiation, and makes it clear that the purpose of the test is to consider the weathering resistance of plastics. It specifies the basic conditions of the test, such as the selection of different types of solar radiation sources, and the requirements for the test site and environmental factors. It also introduces the general content of specimen preparation, exposure methods and monitoring points. This part provides general guidelines for subsequent specific test methods, helps to unify the solar radiation exposure test process for plastics, and promotes the mass improvement and research and development of products in the plastics industry.