This standard specifies a unified method for testing the bending fatigue performance of polymer matrix composites under cyclic loading conditions with constant amplitude and frequency. It covers the complete process from terminology, principles, and equipment requirements to specimen preparation, testing procedures, result processing, and reporting, aiming to provide a reliable basis for accurately evaluating the bending fatigue life and durability of such materials. The core equipment required for performing this test is a fatigue testing machine capable of applying cyclic bending loads, such as an electro-hydraulic servo fatigue testing machine or a high-frequency fatigue testing machine. These devices must be able to precisely control load amplitude and frequency, and apply continuous loading to the specimen until failure, to determine its fatigue performance.