Abstract: Fiber-reinforced cementitious, ECC, material is a typical cohesive-frictional material. To effectively design the load-bearing capacity of ECC structures, it is crucial to accurately describe their three-dimensional strength characteristics. This study reveals the understanding of the tensile and compressive strength of ECC materials, focusing on how fibers influence cohesive and frictional strength. Subsequently, one peridynamic model for ECC material was developed using polyvinyl alcohol (PVA) fiber-reinforced ECC as an example, whose rationality in describing the failure process and strength characteristics were verified. Then the impact of PVA fiber content on the three-dimensional strength and on the strength parameters of ECC materials is analyzed by combining results from triaxial tests with peridynamic simulations. The study identifies the strength parameters necessary for developing a nonlinear unified strength model for ECC materials. The effectiveness of this nonlinear model in representing the three-dimensional strength characteristics of ECC materials is validated against the results of the peridynamic simulations. Overall, the conclusions drawn from this research provide a theoretical basis for establishing a three-dimensional elastoplastic constitutive model for ECC materials, as well as a strength model for analyzing the load-bearing capacity of ECC structures.