Abstract:polynomial distributed lags (PDL) model is proposed for short-term traffic forecasting,the key idea of which is that the time series of traffic condition are affected not only by the own lagged terms,but also by other factors relevant to the traffic condition.The PDL model also assumes that the effects of other factors are distributed to a number of terms.Comparison with the autoregressive integrated moving average (ARIMA) model shows that with the same prediction accuracy as the ARIMA model,the PDL model is more portable and easier but less complicated to implement.This research result provides a new research idea for the short-term traffic flow forecasting theory.