Abstract: To meet the needs of studying impact toughness of welded joint,established a measuring system of impact toughness with high strain rate by combining the Hopkinson device of gas gun loading model with the measuring technique of three point bending specimens in gas gun device of split Hopkinson pressure bar.Some technical problems such as loading,recording,data treatment,dynamic effect and so on have been solved.Impact tests of joint welded with E5015 electrode were carried out using common V-type notch specimen and precast crack V-type notch specimen.Ideal results showed that the design thinking of the system is right,and test data is reliable.