The inclusion of river sand in ECC alters the crack initiation and propagation behavior. As a result, the multiple cracking and pseudo strain-hardening of the river sand ECC (RS-ECC) are different from that of the typical micro-silica sand ECC. This study investigates the strain-hardening criteria for the RS-ECC by considering the matrix as a three-phase material containing pre-existing flaws along the sand/matrix interface with a given size distribution. Micromechanics is used to impart the new mechanisms in the analytic model for the steady-state crack analysis and the formulation of the strain-hardening criteria of ECC incorporating river sand. A probability-based approach is adopted to assess the strain-hardening potential of RS-ECC and validated with experimental results. Results show that the proposed model can predict the tensile properties of RS-ECC, which can be used to guide ingredients selection and components tailoring of RS-ECC to achieve required tensile strain-hardening performance.