Abstract: To study the effects of wall roughness,sudden expansion/contraction,inlet turbulence intensity and cooling channel curvature on heat transfer and fluid flow in cooing channel,three-dimensional turbulent fluid flow and heat transfer were numerically investigated with RSM model,which was used to represent the turbulence;the coolant was gas hydrogen,whose thermophysical properties varied with both temperature and pressure.The results show that,the increase of wall roughness will increase not only the heat transfer but also the pressure loss;the vortex appears on the nearby sudden expansion/contraction point,the turbulence intensity and local pressure loss increase due to the vortex,while the wall temperature decreases at the place where the vortex appears;the coolant inlet turbulence intensity has no effects on the development of flow in cooling channel;the secondary flows which develop due to centrifugal force on the coolant will cause the mass redistribution,leading to heat transfer enhancement at the concave cooling channel but deterioration at convex cooling channel.