Abstract: The relationship between material spheroidization, coercivity and service time of 12 Cr1 MoVG steel was studied by metallographic examination, hard test, mechanical property test and coercivity measurement. The results show that by measuring the coercivity, the spheroidization microstructure characteristics and service time of 12 Cr1 MoVG steel pipe quickly by measuring the coercivity. The results could provide reference for relevant units to carry out pipe cutting treatment and life assessment, and prevent material spheroidization failure.