For cement plants, great attention is being paid to the emission of the pollutant gases, especially NO, CO and CO2. Precalciner is an important equipment in a cement plant in that it can reduce not only the heat loading of rotary kiln but also,the NO emission because of its relative low operating temperature. In this paper, the mechanisms for the formation of NO and CO are analyzed and a numerical simulation technique is applied to model the coal combustion, raw material decomposition and concentration distribution.,of the pollutant gases in a full scale DD-PCR (dual combustion and denitrator process precalciner). The predicted results agree well with the measured data.