Abstract: The dynamic stress concentration and the scattering of SH wave by intermixion and crack are studied by means of Green's function. In order to solve the problem, the first important work is to construct a suitable Green's function, which is the solution of displacement field for elastic half space with intermixion and crack by out plane harmonic line source loading at horizontal surface. The integral equation for determining the unknown forces about the problem can be transformed into algebraic equation and solved numerically. So the dynamic stress concentration factor (DSCF) of crack may be determined. The influence of intermixion on crack DSCF is discussed emphatically, numerical results and discussion are given, so a kind of useful reference for engineering design is provided.