Abstract: A degenerate infinite element is proposed for the case where the three-dimensional infinite element in ABAQUS is only suitable for finite fields using hexahedral elements. This element can be used in the case of using tetrahedral elements in finite regions without redevelopment, and can adapt to more general mesh forms of the model. A calculation formula for the equivalent nodal forces of the degenerated tetrahedral infinite element is presented, and the seismic input methods are analyzed accordingly. The numerical model test results demonstrate that the degraded element has good accuracy and better mesh adaptability, and can be widely used for the analysis of dynamic problems.