Abstract: Analyzing on change factors of China open-end funds scale and founding economic model which can explain the size of the fund changing. Analyzing and forecasting changes on China open fund scale can provide decision-making basis for management and risk control of China open-end fund investment which will have very theoretical and realistic significance. This study on the external factors which effects the fund investment flows. Based on season serial data it found the error correction model to analysis the change of fund size by the example of the open-end stock equity mutual funds in China. This model extends the size of sample data. The results shows us there exists a long-term cointegration relationship among the fund scale changing Y, the net growth rate of the final fund share X1 and the percentage of the Shanghai index changing X2. It analyzes the long term equilibrium relationship and short term fluctuate forecast of the fund flows. From the coefficient estimation, we can see that the adjustment effort is large.