Abstract: The Gleeble-3500 thermal simulation tester is employed to investingate the thermal deformation behaviour of 12CrNi5MoV forged steel at deformation temperatures of 850-200 ℃ and strain rates of 0.1-0.001 s^-1 by using a single-pass compression. The results show that dynamic recrystallisation occurs in 12CrNi5MoV forged steel at high temperatures and low strain rates, and that the recrystallisation doesn't or only partially occurs in 12CrNi5MoV forged steel at low temperatures and high strain rates. Based on the compression curve, the Arrhenius high-temperature principal model of 12CrNi5MoV forged steel is established, and its average relative error is 14.8 %; the Arrhenius high-temperature principal model of 12CrNi5MoV forged steel, which is established by taking strain compensation into consideration, has higher accuracy, with the average relative error 6.1 % and the correlation coefficient of 0.991.