Abstract: Using Gleeble -3800 thermal simulator to add Y-base rare-earth to E36 ship plate steel (hereinafter referred to as the "E36RE ship plate steel"), the thermal simulation experiment research was carried out to investigate the effects of different heat input on the microstructure and mechanical properties of welding heat affected zoneof the E36RE ship plate steel. The results show that with the increase of the cooling time (t8/5), the bainite in the welding heat affects zone reduces gradually; lath-shaped bainite transforms to granular bainite; pearlite appears when cooling time (t8/5) increases to 40 s. When simulating hot line input energy is 78.37 kJ/cm, the microstructure of the simulatedwelding heat affected zone is fine and uniform with good toughness, and the impact toughness is 134.6 J at -40 ℃.