Incorporating steel fibers into cement-based materials effectively prevent the generation and development of microcracks, thus improve anti-crack performance. The stress intensity factor (SIF) solution of the interaction between the crack and steel fiber in the infinite plate under plane stress condition was obtained through the Eshebly equivalent inclusion theory and the maximum circumferential stress criterion. The maximum stress expression of the crack tip of Ⅰ-Ⅱ combined fracture mode with fiber was derived. Through the maximum stress ratio of crack tip after adding steel fiber, the direction, location and the elastic modulus of steel fiber on toughening effect were analyzed. The results show that, the maximum stress around crack tip is reduce by changing the strain field and SIF. The maximum stress ratio of crack tip reaches the minimum value when the steel fiber is perpendicular to the crack and the toughening is significantly affected after steel fiber aligning. Further more, the calculation result shows that the direction of steel fiber is the major factor on toughening effect and little effect on the elastic modulus of steel fiber.