Abstract: Study has been made on the effect of normalization control cooling on mechanical properties and low temperature in pact toughness of 12MnCrNiMoV steel plate. The microstructures of 12MnCrNiMoV steel plate were examined. The results indicate that 12MnCrNiMoV steel plate treated with normalization control cooling is higher in strength and toughness than that of one treated with air cooling. The value of A _kv,-40℃ was increased up to 45%, the T _FAT50 was lowered 20℃. The microstructure observations show that the microstructures of 12MnCrNiMoV steel treated with normalization control cooling were mainly lath marten site. After high temperature tempering, the structure were turned into lath ferrite with fine carbides dispersed homogeneously, which was attributed to properties of 12MnCrNiMoV steel.