Abstract: In this paper,a soft-hard heterogencous cracked body has been established as the model for analysis.The fatigue testing of the heterogeneous plates showed that the mechanical heterogeneity affected the fatigue crack growth rate.The numerical simulation of BEM,boundary element method,was used for analysing the heterogeneous fatigue bodies.The smaller the distance between the crack surface and the interface of soft-hard region is,the smaller △J (the amplitude of J-integral in the same growth step) is,and the fatigue crack growth rate become.The influence of heterogeneity on the fatigue crack growth rate is mainly determined by △J.