The original austenite and quenched martensite structures of press hot steel with vanadium have been investigated by means of optical microscope and scanning electron microscope. The results show that V exists in the form of dispersed nanoscale VC or (V, Ti) C complex carbide in austenite, which has a significant effect on the refinement of the original austenite grain size. When the heating temperature is higher than 900 °C, the V(C, N) decomposition results in the rapid decrease of austenite grain refinement, however, the austenite grains are still refined due to the drag effect of Ti(C, N) on V(C, N). The combination of vanadium and carbon in austenite can reduce the content of C in quenched martensite, which could promote the formation of strip martensite and avoid the formation of twinned martensite, so as to improve the toughness of materials and improve the problem of hydrogen-induced cracking.