Abstract: This paper aims at the low accuracy of emission function and uses ASPEN PLUS to simulate the process of boiler combustion. Then a more precise emission function is obtained from regression analysis of the data from boiler combustion by SPSS. The authors establish a dispatch model based on the more precise emission function by using the lowest environmental cost and fuel cost as the objective. Simulation shows the dispatching model based on more precise emission function is more effective in emission reduction.