Abstract: Through importing Fourier progression and ARMA(n,n-1) model, a model of econ omic prediction of time series of short or middle periods is set up. In this mod el, the method of curve fitting is used to eliminate trends of time series; the method of Fourier progression is used to analyze the fluctuation of time series with seasons; the model of ARMA(n,n-1) is used to deal with the perturbati on of time series. Finally, an example is given to demonstrate the availability of the model.