Abstract: In the process of achieving the goal of carbon peak and carbon neutralization in the power system, the power supply structure and grid form will change significantly, and the system cost will also change accordingly. On the basis of comprehensive consideration of the changes in power supply structure, power generation cost, fuel cost, grid investment and other factors, this paper adopts the business period method and the “cost + income” model to forecast the cost and price level of power system in the mid to long-term. The research results show that the cost of each link of the power system will increase in the future, among which the cost of the power supply side will increase rapidly before 2040 and tends to be relatively stable afterwards, while the cost of the power grid side will increase slightly. This study can provide a reference for further improving the electricity price mechanism and marketization system, as well as strengthening the power system cost facilitation and fair sharing.