In order to evaluate the mechanical properties of high strength Q460 steel after cooling from high temperature, high strength Q460 steel was heated by electric furnace and cooled down with natural cooling or water cooling, then the tensile test was carried out. The strain stress curve, yield strength, ultimate strength, elastic modulus and ultimate elongation of high strength Q460 steel after cooling from high temperature were determined. The yield strength, ultimate strength and elastic modulus of high strength Q460 steel after cooling from high temperature were compared with that of ordinary Q235 steel. The results show that the mechanical properties of high strength Q460 steel change after high temperature compared with that at room temperature, especially when the temperature exceeds 700℃. When the temperature exceeds 700℃, cooling method has great influence on ultimate strength and ultimate elongation of high strength Q460 steel, the ultimate strength of high strength Q460 steel under water cooling is much higher than that under natural cooling, the ultimate elongation of high strength Q460 steel under water cooling is much lower than that under natural cooling. The influence of cooling method on yield strength and elastic modulus is not notable. The reduction factors of yield strength, tensile strength and elastic modulus of high strength Q460 steel after cooling from high temperature are different from those of ordinary Q235 steel.