Abstract: Considering the physical relations and dynamic properties among state variables of an atmospheric system,this paper introduces a phase space projective method for operational monthly precipitation forecasts. This method not only takes into account direct factors of precipitation at a local point but also indirect factors of the locality and precipitation and the influence of periphery. So this paper has enrlched the phase space method of long range forecast. The verifications of trial forecasts for a length of 60 months show that the forecast accuracy of anomaly sign of this method can reach 40/60=67% and 23/30=77% in rainy seasons (May-October).The forecast effects of this method are sharply superior over the present operational level of long-range forecasts.