Abstract: The mixed method of boundary element and fractal finite element is adopted to solve the cracked structure-acoustic coupling problems. The fractal two-level finite element method is employed to model the cracked structure, which can reduce the degree of freedoms greatly, and the boundary element method is used to evaluate the exterior acoustic field which can satisfy automatically infinity radiation condition. Numerical examples show that the resonance frequency is lower with the depth of the crack increase, and the effect on the acoustical field by the crack is particularly pronounced in vicinity of the crack tip.