Many economic problems can be formulated as optimization problems. Econometricians have long devoted their efforts to construct the econometric equation systems, while the corresponding objective functions receive few attentions. In recent twenty years, some techniques to construct the objective functions with economic implications have been developed, which might have a potential in economic decision-making.In the paper we apply the method of constructing objective function to design an optimization model for monthly monetary planning of China. The real monthly data from 1991 to 1999 are used to evaluate the monthly economic situation. Our empirical experiment shows that the model gives a good short-term forecasting.