The effect of heat treatment parameters on the strength and plasticity and the metallographic structures and substructures of Cr12W2MoVNbNB steel has been studied. The regularity among the different heat treatment processes,the strength and plasticity, the feature of its structure and substructure have been analyzed. The results show that after being normalized and tempered, the structure of tempered lath martensite and blocky ferrite has been acquired, the grains do not grow up with the increasing of normalizing temperatures. During the tempering process, instead of recrystallization,polygonization of tempered martensite only takes place. Tempering temperature is chief effective factor to the strength of the steel. Moreover the proper heat treatment parameters of Crl 2W2MoVNbNB steel have been given.