Abstract: The influence of Si and Mn content on the mechanical properties and banded structure of DH36 marine steel plate in the hot-rolled and normalized states with thickness of 30 mm was analyzed in laboratory. The results show that the microstructure at the center of the hot-rolled DH36 steel are mainly composed of ferrite and pearlite, and the cooling rate of the surface of steel plate is relatively large, forming bainite and promoting the acicular ferrite transformation. The strength of DH36 steel plate with different Si and Mn content are not significantly different, and the strength and impact properties meet the requirements of mechanical properties of DH36 steel plate, but DH36 steel with high Si content has a large number of mixed crystal structure, resulting in poor impact properties at -40 ℃. After normalizing treatment, the strength of DH36 steel plate decreases, and the elongation and impact toughness are improved. It is failed to improve the impact properties of DH36 steel with high Si content after short-term normalizing. However, prolonged normalizing results in a significant decrease in the tensile strength. The segregation of C and Mn elements is the main factor leading to the formation of banded structure in DH36 steel. The banded structure grade of high Si content DH36 steel is relatively low, which is mainly attributed to the improvement of C element activity and the redistribution process of Mn element in ferrite/carburite phases.