The temperature distribution along the thickness direction of AZ3lB Mg alloy was measured during rolling with heated rolls, basing on the previous study of temperature rise effect during rolling with cold (RT) rolls. The effect of different rolling conditions on temperature distribution and its relation with microstructure were investigated. On this basis, simplified energy-based state equations were established to predict temperature rises. The results show the temperature rises during rolling both increased with either increased reduction or decreased initial rolling temperature. The roll temperature had obvious effects on surface temperature and overall temperature rise. As a result, the amount of twin in surface layer decreased sharply and the overall recrystallization zone increased during rolling with heated roll. The calculated results by energy-based state equations were in good agreement with experimental ones.