分析了用传统的强度理论设计方法来校核含裂纹体的构件强度存在的问题。重点研究了平板厚度和裂纹位置分布及尺寸对裂纹尖端应力强度因子的影响，结果表明：沿垂直方向应力强度因子分布呈现中间小两边大，提高构件沿裂纹扩展方向的长度，应力强度因子的分布呈现截止区与局部增大区，而提高构件沿垂直于裂纹扩展方向的长度，应力强度因子的分布只出现截止区，沿厚度方向应力强度因子分布规律呈现表层小于中心层，其裂纹尖端的扩展位移为椭圆形。通过裂纹多因素分析为工程构件的裂纹扩展断裂提供理论性的指导。“,”Analyzes the problem that existed in checking the strength of the part with crack using traditional design method. According to the displacement extrapolation method,The paper analyzes the kind of crack length, thickness and plate size have effect on the stress intensity factor. the result shows that: The stress intensity factor in different crack location present the distribution rules of small middle big at both.The distribution of stress intensity factor occur cut-off region and part of increasing region when increase the frame length along the direction of crack growth. It occur only cut-off region when increase the framer length along vertical the direction of crack growth.Along the direction of thinness, the distribution of stress intensity factor present the rules of the big central position the small surface position,while the displacement of crack tip growth is ellipse.It provides theoretical guidance to crack extension fracture in engineering components by multiple factors analysis.