Abstract: The high extension flange steel was prepared based on traditional hot rolling technology of double-phase steel, and the effects of coiling temperature on the microstructure, mechanical properties, flange properties and precipitation strengthening were revealed.The results show that with the increase of coiling temperature, the lath-shaped bainite in structure gradually evolves into spherical bainite, and the bainite is distributed uniformly around the ferrite.The precipitation in ferrite is increased gradually due to the ultra-fast cooling and the increase of coiling temperature.The movable dislocation effect of the hot rolled plate increases the yield strength from 541 MPa to 655 MPa, the microstructure change and the precipitate effect reduces the tensile strength from 830 MPa to 788 MPa, and the elongation after fracture increases from 17.2%to 25.6%.With the increase of coiling temperature, the expanding hole mechanism of hot-rolled plate changes from the linear transgranular fracture to the sinuous ductile fracture, and the expanding hole performance finally improves significantly from 52%to 83%.