The invention belongs to the technical field of explosive mechanics and mechanics experiments and relates to an experimental device for measuring dynamic response of a material under underwater explosion. The device comprises a water tank system, a force measurement base system, a measurement system, a material which is to be detected and has unknown mechanical property parameters, and a reference material having known mechanical property parameters. In an experiment, the reference material having known mechanical property parameters and the size the same to that of the material to be detected is tested, then the material to be detected is tested, and the signals acquired by the two tests are compared so that dynamic response of a material to be detected under underwater explosion and basic mechanical property parameters of the material to be detected are obtained. The experimental device can really simulate the dynamic response of different materials to the underwater explosion shock wave. Compared with the traditional on-site underwater explosion experiment device, the experimental device has the advantages of wide application range and simple and convenient operation, realizes the same purpose and greatly reduces an experimental cost. Through a rotary lifting rod, a test platform can move up and down so that measurement of dynamic response of materials having different sizes under action of underwater explosion shock wave is realized.