Abstract: The influence of the heat treatment process on the performance of high strength steel plate for a nuclear power plant was discussed. High-strength steel plates were heat-treated under different quenching process parameters + different tempering process parameters, followed by tensile test and Charpy impact test. The steel plate microstructure observation and sample fracture analysis were also performed. The results show that the strength and toughness of the steel plate are changed under different heat treatment conditions. After 920 ℃/（30-60） min quenching + 635 ℃/（120-240） min tempering, the steel plate can obtain excellent comprehensive performance after heat treatment under this condition. The microstructure is mainly tempered sorbite, and fine carbides are evenly distributed. The tensile sample fracture and impact sample fracture are mainly dimple, which show better toughness.