Abstract: With the development of spot market construction, the mechanism and strategy of trans-provincial hydropower participating in the spot market have attracted more and more attention in the industry. Trans-provincial hydropower has its unique characteristics and cost model. In terms of its delivery in the medium and long-term contracts, a physical execution mechanism of the decomposition curve in the medium and long-term contracts is designed in view of the features of multi-functional constraints, large volume and multi provincial consumption of trans-provincial hydropower. In terms of the day ahead market, the cost of hydropower is directly related to the opportunity cost corresponding to the water consumption volume rather than to the power. An energy-based incremental bidding mechanism of the day ahead market is designed. In the aspect of trans-provincial hydropower trading strategy, the strategy and model of the medium and long-term contract decomposition method based on water value is proposed in this paper, so that the future expected benefits will be fully taken into account in the delivery of the medium and long-term contracts. In order to solve the problem of lack of marginal cost reference of hydropower, a decision-making model for the incremental bidding of the day ahead is constructed. The marginal water value curve is calculated as the reference for the day ahead market bidding of trans-provincial hydropower.