Abstract：This paper introduces the time series prediction model of ionospheric VTEC improved by wavelet decomposition. The VTEC grid data released by IGS in 2013 are taken as experimental data to model point by point. Firstly, the VTEC series of 5 112 grid points are decomposed using db4 separately, then predicted using time series analysis, and finally reconstructed to predict the VTEC. The forecast bias and RMSE of the common prediction method and the improved method are compared. The result shows that the precision and the proportion of high accuracy using the improved method are better than the common prediction method. The improved method achieves the aim of raising accuracy.