Abstract: Strong heat and mass transfer processes exist in the vertical pipe of quench chamber. The content of water vapor in the gas phase resulted from the high temperature of the gas phase is so high that the water gas shift reaction will have an effect on the composition of raw syngas. Firstly, based on the flow field and partitions of the pulverized coal gasifier, a reactor network model of gasification chamber is built to obtain the results of the gasifier outlet gas, such as temperature and composition of the gasifier outlet gas. The coal pyrolysis process, homogeneous and heterogeneous reactions are all included in the model. The ratio of evaporated water to the inlet cooling water is obtained through the numerical simulation of the heat and mass transfer process in the vertical pipe. Then, a quench chamber model is built in which the vertical pipe and the liquid pool are simulated by a plug flow reactor and a separator respectively. A mathematical model involving the gasification chamber and quench chamber of an entrained flow pulverized coal gasifier is developed. The effects of the feeding rate and temperature of cooling water on composition of raw syngas are investigated respectively by the mathematical model. The results show that the mass of evaporated cooling water accounts for 4.4% of the inlet cooling water in the vertical pipe. CO volume fraction of gasifier outlet gas decreased by 12.5%, H₂ volume fraction increased by 5.8%, and the volume fraction of effective gas decreased by 6.7% during the quench process. The results of composition of raw syngas meet well with the industrial data. Feeding rate and temperature of cooling water have little influence on the composition of raw syngas.