Abstract: Under the background of electric power system reform, the power supply and sale mechanism of onshore power supply was studied. Firstly, the types and effects of onshore power supply were introduced. The general situation and influence of electric power system reform were also described. After that, the present situation and existing problems of onshore power supply were analyzed. To increase the economic benefit of onshore power supply, five methods have been proposed to establish a new power supply and sale mechanism of onshore power supply. The feasibility and effectiveness of the proposed methods were verified based on an actual onshore power project of the port of Tianjin. Research showed that the improved power supply and sale mechanism of onshore power supply will helpful to reduce the application cost of onshore power supply. Port enterprises should be encouraged to purchase electric power in the power sale market, and electric power sellers should be encouraged to more participate in the projects of onshore power supply.