In the previous researches, when the economic factor forecasting solution of urbanization was used into practice, the influence on urbanization produced by the level of present economic development always was regarded as the only factor to be considered. So the accuracy of the forecasting should be decreased seriously by ignoring some important effects. In this paper, taking Gansu province as an example, the authors tried to forecast the level of urbanization in Gansu province on the basis of the PDL (polynomial distributed lags) Models. At the same time, the ARIMA Models and CPPS software were also applied in the research.