Abundant experimental studies reveal that failure of multicrystalline rocks is mainly caused by intercrystalline fracture which occurs along the boundaries of crystalline gains of the rocks.The propagation of the cracks along the kink grain boundaries is in the form of winged-crack.At present,there are many methods to calculate the winged cracks and most results are obtained based on equivalent method under the condition of homogeneous medium.The computational process by using ANSYS Parametric Design Language was established in this paper.The SIF(stress intensity factor)of winged crack tip at the interface of the intercrystalline crack are obtained via numerical extrapolation method for the nodes displacement.Then a comparison is made with the HN approximate calculation model.Differences of crack propagation between the heterogeneous brittle material and the homogeneous material are also analyzed and the influence on the crack propagation caused by the geometrical characteristics of the crystalline grain and the materials heterogeneity degree(Dundurs parameter)are studied.The results shows the characteristics of crack propagation are influenced significantly by degree of material heterogeneity which result larger K1 values and direction of crack propagation.