Abstract: With the continuous promotion and improvement of the power spot market, the diversification of power generation side subjects makes the bidding environment of power generation subjects more intense. The establishment of the bidding unit is conducive to improving the ability of power generation enterprises to resist the risk of market bidding. This paper analyzes the impact of different river basin hydrological conditions, multi-element development subjects and the scale attribute of power stations on the bidding of power generation enterprises.By taking the three main factors of power generation enterprises and grid access points as indicators, this paper proposes a bidding unit construction method based on density peak clustering, and the method is applied to 67 power stations in the main river basins in Southwest China. The results show that the construction of bidding unit is of practical significance to improve the bidding capacity of hydropower. The unit scheme is relatively consistent with the unified dispatching unit specified by the power grid, which verifies that the model is reasonable and feasible. It can provide a new idea for power generation enterprises to participate in power spot market bidding.