Regenerative cooling is considered one of the most effective cooling methods used in liquid rocket engines and has been widely studied in recent years.But the effect of the non-uniform flow in cooling channels caused by inlet and outlet manifolds did not attract much attention.In this paper,we carried out the coupled flow and heat transfer of combustion and regenerative cooling in a LOX/Methane (LOX means liquid oxygen) engine and compared the results with and without manifolds.Then,three different configurations of the inlet and outlet manifolds were also discussed.The results show that the parameters averaged in the circumferential direction are less affected by the manifolds.However,the existence of the manifolds will make the distribution of mass flow rate as well as wall temperature non-uniform along the circumferential direction.In addition,when the angles between inlet and outlet are 0°,90° and 180°,the maximum temperature difference along the circumference of throat increases by 90.1％,151.2％ and 229.5％,respectively,compared with that without manifolds.This indicates that the larger the angle between inlet and outlet,the greater the non-uniformity of mass flow rate and wall temperature along the circumferential direction.As a result,extra thermal stress will be generated which could cause some negative effects on the rocket engines.