Abstract: By means of CFD，geometrical model development and gridding compartmentalization of the radiation segment of ethylene cracking furnace as calculation field were performed. By using mathematical models suitable for combustion of ethylene cracking furnace，k-ε turbulent flow model，composition PDF transport model and DO radiation model，the numerical simulation of combustion，flow，heat and mass transfer process was studied. Velocity，temperature，concentration were distributed asymmetrically. The result was in agreement with the industrial process.This validated the reliability and rationality of mathematical models of combustion process and provided the theoretical reference for optimizing the structure of cracking furnace.