A model based on Avrami equation and Scheil’s additivity rule was proposed to simulate the phase transformation inplain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of composition, coolingrate, primary austenite grain size and retained strain has been taken into account. It can be used to calculate the phasefraction transformed at different temperatures during continuous cooling. The phase equilibrium and transformationstarting temperature can be determined by using Thermo-Calc and DICTRA. The simulated results containing thetransformation at starting and finishing temperatures, A_(e1), A_(e3) and the maximum volume fraction for Q235B, wereobtained. The calculated phase volume fractions are in good agreement with the experimental results. A model based on Avrami equation and Scheil’s additivity rule was proposed to simulate the phase transformation inplain carbon steels during continuous cooling in hot strip mill. In this model, a wide range of composition, coolingrate, primary austenite grain size and retained strain has been taken The phase equilibrium and transformation start temperature can determined by using Thermo-Calc and DICTRA. The simulated results containing the transformation at starting and finishing temperatures, A_ (e1 ), A_ (e3) and the maximum volume fraction for Q235B, wereobtained. The calculated phase volume fractions are in good agreement with the experimental results.