The main purpose of this paper is to establish ARIMA model and SVR model to analyze and forecast the stock price composite index. This paper takes CSI 300 Index as an example and takes the closing price of T+1 day as the main research variable. Firstly, the linear part of the stock index is predicted by using the traditional ARIMA model. Then, the SVR model is constructed to deal with the nonlinear factors of the stock index by considering the variables such as the closing price and trading volume on t day. Considering the shortcomings of the single model, the first mock exam is to build two models and compare the prediction results with the ARIMA-SVR models. The results show that ARIMA-SVR model improves the prediction accuracy of the model to a certain extent, and can accurately predict the trend and fluctuation of CSI 300 Index in the short term, and can provide certain guidance for investors' investment decisions.