The effects of shape memory alloy (SMA) fiber with different content and different diameter on tensile stress-strain relationship, residual strain, crack width and crack recovery rate of engineered cementitious composites (ECC) were studied by uniaxial cyclic tensile test. The results show that the addition of knotted-shaped SMA fiber improves the ultimate strain and ultimate tensile strength of ECC, and the strain recovery rate of pure ECC without SMA fiber is 12% in the late cycle. The strain recovery rate of SMAF-ECC specimens doped with 1.00% (volume fraction) 0.5 mm SMA fiber is as high as 69%, and the crack recovery rate of SMA fiber with 1.00% (volume fraction) 0.5 mm diameter enhanced ECC is 77%. If the fiber diameter grows in a certain range, the strain and fracture recovery rate can be improved, if the fiber diameter is too small, the recovery rate will decrease. The research results provide a theoretical basis for the popularization and application of the new SMAF-ECC specimens.