Abstract: The material heterogeneity and the spatial distribution of steel fibers in Steel Fiber-Reinforced Cementitious Composites (SFRCC) can significantly impact the mechanical properties of SFRCC. Based on parameterized language and the Weibull distribution density function, this study established a heterogeneous SFRCC numerical model composed of steel fibers, of cement mortar matrix, and of interface transition zones, and simulated the uniaxial tensile failure process of SFRCC specimens under different degrees of heterogeneity and the average orientation coefficients of steel fibers. The results show that: the incremental homogeneity markedly enhances the uniaxial tensile strength of SFRCC, and exerts a superimposed reinforcement effect with one growth average orientation coefficient. The incremental homogeneity enhances the strength of SFRCC, improves brittleness, and reduces toughness. The growth average orientation coefficient will weaken the adverse effects of the incremental homogeneity on SFRCC. The research results further reveal the tensile damage failure mechanism of SFRCC under the combined influence of the homogeneity and average orientation coefficient.