The invention, which belongs to the technical field of dynamic load testing, relates to a loading device and method for a stretch dynamic load test of a self-sealing type shedding joint. The loading device comprises a rigid base, a transmission platform, a loading platform, a rigid screw connecting the loading platform with the transmission platform, a drop hammer, an acceleration sensor, a dynamic load sensor, an adjustment mass block, variable-thickness rubber pads for adjusting load acting time and values, a positioning pulley, a flexible rope, and a pressing block for fixing the flexible rope. According to the invention, the loading device has advantages of simple structure, great convenience in processing, and great convenience in operation. Compared with the existing reported stretchdynamic load device only emphasizing acquisition of stretch load information, the provided loading device pay attention to three factors including the stretch dynamic load acting time, a fixture speed changing amount, and a load size and coordinates the coupling effects of the three factors, thereby completing the test task effectively. Therefore, the loading device and method have the importantengineering significance in determining the stretch disconnecting dynamic load of the self-sealing type shedding joint.