In the present work, detailed studies were made on the transformation characteristics, microstructure and mechanical properties of heavy shell ring (HSR) in the spray cooling process. The spray cooling device of HSR was designed. The 2.25Cr1Mo0.25V steel used in production of HSR for hydrogenation reactor was selected as the testing material. The simulation of spray cooling of HSR was carried out on ABAQUS. The constitutive model and continuous cooling transformation (CCT) diagram of 2.25Cr1Mo0.25V were determined. CCT diagram, metallograph and SEM results show that the bainite forms throughout the cooling rate range from 0.5 to 10 ℃/s, and martensite begins to be produced by increasing the cooling rate higher than 60℃/s; when the cooling rate is 10 ℃/s, with the increase of the deformation degrees, the ferrite grain size becomes small, the yield strength and tensile strength increase, the elongation decrease, So it is good for refining the grain to increase the deformation. The yield strength, tensile strength and elongation were obtained under different cooling technology.