Cracks in engineering structures are prone to rapidly propagate under dynamic loading, leading to low-stress brittle fracture failure, which severely impacts the safety of the structure. Within the framework of the finite element method with generalized degrees of freedom, the Williams element with generalized degrees of freedom (W element) was proposed for the analysis of DSIFs(dynamic stress intensity factors) of crack tip under dynamic load. The approximate solution of the load vector of the element in the singular region was derived by assuming that its displacement approximately satisfies the rigid body rotation theory. The global governing equation of the model was solved by Newmark integral method, and the corresponding generalized parameters were directly substituted into the formula to obtain DSIFs at the crack tip. Examples were employed to analyze the influence of key parameters of W element on DSIFs at the crack tip, investigation shows that the proposed method achieves higher calculation accuracy with the radial discrete scale factor is 0.95, the number of radial discrete elements is 400, the number of series terms is 12.