The curves of hardenability of 07MnCrMoR hydropower steel plate are tested

and the 100 mm thick tested steel plate is quenched and tempered by heat treatment furnace and quenching equipment

and the structure of and mechanical properties of test steel are observed and measured. The results show that with increasing the distance from cooling end the microstructure of tested steel transforms from martensite to granular bainite

and transforms to ferrite and granular bainite microstructure at 50 mm from the water-cooled end. The lath bainite + granular bainite + pre-eutectoid ferrite are obtained in test steel plate after quenching by queching equipment

then transforming into ferrite + granular bainite after tempered

and a large number of carbides precipitating at ferrite matrix and grain boundary. The most reasonable heat treatment process of the test steel is water-cooled quenching at 930 ℃ for 30 min and air-cooled at 660℃ for 60 min.