Abstract: The effects of different heating temperatures on the microstructure and mechanical properties of marine engineering steel were investigated by SEM and EBSD techniques. The results show that the microstructure of the steel plates rolled at different heating temperatures is mixed structure of ferrite +fibrite. The tensile properties of the steel are similar at room temperature, while the disparity in low-temperature impact absorbing energy at-84 ℃ was found to be substantial, the maximum difference of the low-temperature shock work of-84 ℃ is nearly 120 J. With the increase of heating temperature,the average grain size of the steel plate increases, the low temperature impact work decreases, the heart generates band microstructure and the proportion of small angle grain boundary increases, and the shape of ferrite changes from quasi-polygonal ferrite（QF） to polygonal ferrite（PF）. At heating temperature of 1150 ℃, the steel exhibits the most favorable comprehensive of mechanical properties.