The flexural capacity and deflections of steel fiber reinforced concrete (SFRC) beams were discussed in this paper based on the nonlinear fracture mechanics. Analytical Equations describing the flexural capacity and deflections of the SFRC flexural members were proposed. Five series of steel fiber reinforced mortar beam specimens with different steel fiber volume fractions were tested. It is found that the flexural capacity before and after cracking depends largely on the tensile strength and the residual tensile strength of SFRC, respectively. The proposed design method can reflect not only the ability of SFRC to resist plastic strain, but also its contributions to toughness and crack arresting ability.