Abstract: To study the heat transfer characteristics of expander cycle regeneratively-cooled thrust chamber,three dimension computational models of a referenced thrust chamber and two expander cycle thrust chambers with different area ratio were established.The coolant heat pick-up,pressure loss in the cooling circuit,wall temperature and heat flux distribution were calculated by numerical simulation.Influence of increased length of chamber cylinder,different cooling routing and area ratio were investigated.Governing equations were discrete with two order upstream scheme.Numerical results show that when a converse cooling is taken,the area of hot gas wall surface of chamber is increased 70% by increased length of chamber cylinder and the coolant heat pick-up is increased about as much as one time;while the selected co-flow cooling routing is employed,the pressure loss is decreased in cooling circuit but the coolant heat pick-up is less than the converse cooling and this cooling routing leads higher wall temperature at the throat.