The invention relates to the field of hydropower generation and dispatching, and discloses a long-term joint peak regulation dispatching method for trans-provincial interconnected hydropower stations. The technical scheme is as follows: a multi-objective optimization model of hydropower stations is set up with the goal of maximizing the amount of power generation and minimizing the peak-valley ratio of a typical day in the dry season, by the use of trans-provincial and trans-regional interbasin hydrological characteristics and the regulation performance difference among power supplies, the power stations are grouped according to an output interval of each power station and the calculation sequence of the power stations is coordinated by stages; and the optimal water level process of sending and receiving end hydropower stations is optimized by using a step by step optimization and dynamic planning successive approximation coupling algorithm and a sending end faced load is reconstructed according to transmission restriction constraints of a trans-provincial DC tie line, the output process of the typical day is determined by a successive load shedding strategy, and a long-term power distribution scheme of the hydropower stations and the electric power process of the typical day in each month are obtained through iterative optimization. The method of the invention can make full use of compensating regulation characteristics of the sending and receiving end hydropower stations, effectively responds to the long-term power demand of a power grid and the short-term peak regulation demand, and meets the actual needs of the trans-provincial and trans-regional dispatching of a giant hydropower station.