The invention relates to high strength and high tenacity steel for coupler knuckle forging and a heat treatment method of steel. Compared with the prior art, the tensile strength of the steel prepared through the method is larger than or equal to 1000 MPa, the yield strength is larger than or equal to 900 MPa, the percentage elongation after fracture is larger than or equal to 24%, the -40 DEG C ballistic work (KV2) is larger than or equal to 50 J. Compared with common steel for coupler knuckle forging, the steel type has the beneficial effects that the strength of a coupler tail frame is obviously improved, the toughness index and the plastic index are improved to a certain extent at the same time, and the service performance of the coupler tail frame is obviously improved.