Aiming at the problems that the modelling parameters of hydropower units are difficult to obtain and the simplified models of hydropower units are not accurate enough, this paper proposes a mid- and long-term unit system model and sequence update power generation strategy for hydropower stations suitable for engineering applications. A set of methods for simulating annual hourly inflow flow based on scenario division are proposed, and the obtained simulation data is used as the input for the modelling of hydropower stations. Then, according to the measured data of the power station, a medium and long-term hydropower station system model considering the change of the reservoir water level and without the variable of the water volume of the reservoir is given. Finally, combined with the timing power generation strategy of the hydropower station, the medium and long-term unit scheduling method of the hydropower station is obtained.