As an important fracture parameter,the stress intensity factor plays a crucial role in the fracture analysis of engineering components. Based on the theory of J,2, integral and the bending theory in material mechanics,this paper analyzes the stress intensity factors of 60 degree thin-walled equiangular steel corner cracks and edge cracks under tensile and bending loads,and gives a simple and practical method to determine the stress. The method of the intensity factor,the method given can obtain a closed solution,and the calculation is simple. The results are compared with the finite element solution,and the effectiveness of the calculation method is further pointed out.