Abstract: Axial cyclic tensile and compressive fatigue tests, forward three-point bending fatigue tests, and lateral three-point bending fatigue tests were conducted on FH40+317L explosive composite steel plates at room temperature and -60 ℃, respectively. The test results and fracture morphology were analyzed. The results show that under axial cyclic tensile and compressive loads and forward three-point bending loads, the crack initiation positions were located in the base layer and the composite layer, respectively. At this time, the initiation behavior was related to the material properties and stress state of the constituent layers. Under lateral three-point bending load, the crack initiation position was located at the interface, indicating that the interface was the weak point of the composite steel plate due to the presence of defects, which needed to be carefully considered in fracture prevention design.