Abstract: In order to analyze the runoff situation of Xiaojinchuan river basin, Markov chain model is used to predict the annual runoff situation. Combined with the changes of historical inflow, by calculating the Markov transition probability of the mutual transformation of abundant, normal and dry in history, the runoff situation of Mupo hydropower station in the next year is predicted according to the inflow situation of that year. Taking the situation prediction of Mupo hydropower station in 2018 for example, the case analysis is carried out. The results show that the prediction results are consistent with the actual results, and the runoff situation prediction analysis method has strong practicability, which provides a practical idea and method for runoff situation prediction analysis.