The model of forcasting the production of wheat and barley by the weighting method of Limit production is developed based on the production of barley and wheat,agricultural technology and weather data. The model is:>y=y_M-y_农-y_灾-y_气 or y=y_M[1-(∑a_i+∑b_j+∑c_n)] It is adopted to forecast the production of barley and wheat in the Yancheng area. Experimental forecasts in the past suggest that the error of the model is less than 5%.