The pre-listed balancing mechanism for monthly deviation is an effective method to deal with the power generation units imbalance electric energy in China's medium and long-term electricity transactions, but the traditional dispatching method is difficult to adapt to this mechanism. Therefore, under the pre-listed balancing mechanism for monthly deviation, a monthly rolling dispatching method for the imbalance electric energy in the power system including hydropower, thermal power and wind power is proposed. Firstly, a monthly electricity decomposition model considering the fairness of parties contract completion schedule is proposed. Secondly, based on the decomposed contract electricity, a day ahead scheduling model and a intraday scheduling model for power system including hydropower, thermal power and wind power are established. The objective function is to minimize the cost of emission reduction and balancing cost. Finally, the balancing cost of the monthly contract power deviation of generation units is minimized by rolling the daily deviation power in the month. Simulation results show that the proposed scheduling model and method can effectively reduce the monthly contract power deviation of generation units and the balancing cost, take into account the requirements of emission reduction.