Abstract: Through the microstructure observation and mechanical properties tests such as tensile, impact and hardness test, the effects of heat treatment processes including heating temperature, holding time and cooling mode on the microstructure and properties of Q245R steel plate were studied. The results show that heating temperature and cooling mode had greater influence on performance of Q245R steel plate. Heating the steel plate at the temperature over Ac1 for proper time and then air cooling, could properly reduce the hardness and strength and improve the toughness of the steel plate, and increasing the holding time, the strength and hardness of the steel plate would also decrease. When heating the steel plate at the temperature over Ac1 for proper time and then water cooling, the higher the heating temperature was, and the higher strength and hardness of the steel plate were and the lower the toughness was.