The effect of rolling process on the microstructure and performance of steel API2W50 in marine engineering structure was studied. The results show that the rolling process of thermomechanical control processing (TMCP)is divided into two stages, above 1000 ℃ and below 950 ℃. The final rolling temperature is controlled at 820 ℃ and then decreases to  620 ℃ by watercooling after rolling. After TMCP, the tensile strength of steel API2W50 reaches 540 MPa, the elongation is 27%, the longitudinal impact toughness at -40 ℃ reaches 279 J , and the horizontal impact toughness at -40 ℃ reaches 215 J, in which the comprehensive mechanical property of steel sheet is the best. Moreover, the microstructure of steel is a mixture of bainite, ferrite and pearlite, and the grain size is uniform and small. Thus, the comprehensive mechanical property reaches the goal of development, which has the industrial trial production conditions.