The invention discloses a suddenly applied load testing device. The suddenly applied load testing device comprises a support, a tension sensor, a cable force adjusting device, a cable breaking device, a gravity loading device and a controller, wherein the upper end of the cable force adjusting device is connected with the top of the support; an output end of the cable force adjusting device is connected with the upper end of the tension sensor through a rope; the lower end of the tension sensor is connected with the upper end of the cable breaking device; the lower end of the cable breaking device is connected with the upper end of the gravity loading device; the lower end surface of the gravity loading device is in contact with the upper surface of a test piece; an output end of the tension sensor is connected with an input end of the controller; and an output end of the controller is connected with a control end of the cable force adjusting device. By the device, instant compression strength of the test piece can be quantitatively analyzed.