Quench chamber is the most important component in the coal gasifier, and is easy to break. In older to find the pattern of turbulent flow and heat tratrsfer of synthetic gas in the Vertical downward pipe, a numerical medal based on analyzig the flow and heat tl-atrsfer features of the vertical pipe in quench chamber is first presented. The variatiotrs of temperature, velocity of synthetic gas with the char, ge in ler, gth and radius of the vertical pipe and the velocity of the gas are obtained, and the effect of l-adiation is found. The pattern of turbulent flow and heat tl-attsfer of synthetic gas in the vertical pipe is further revealed.