Abstract: The calcium silicate hydrate gel produced by the reaction of fly ash and cement can improve the interface structure between aggregate and cement, thus improving the toughness of polyvinyl alcohol fiber reinforced engineered cementitious composites (PVA-ECC). To determine the optimal fly ash content range of PVA-ECC and establish its evaluation index for obtaining high tensile strain, the influence of fly ash content on the strain hardening performance of PVA-ECC was studied by tensile test under the premise of ensuring the good fluidity of PVA-ECC with different mix ratios, and the failure characteristics at the fracture of specimens were studied by optical scanning. Three kinds of different fiber damage modes of PVA-ECC index of tensile stress value such as "Pull-out type" "Fracture type" and "Slip-hardening type" were established. Results show that when the fly ash content is 45%-65%, the tensile properties of PVA-ECC increase with the increase of the fly ash content. When the fly ash content is 60%-65%, the tensile property of PVA-ECC is the best.