Abstract: A view of the nonstationary nature of runoff series, the cointegration theory is introduced into the analysis of runoff to establish reliable mathematical model.Taking the Yellow River as an example, through unit root testing and cointegration testing, the error correction model which can describe the cointegration relationship between the runoff of the upper and lower reaches is set up.In this way the initial cointegration forecasting model is set up.The results show that the forecasting model is feasible.

Key words: runoff, cointegration theory, unit root, error correction