Abstract: Heat transfer experiments of supercritical water in circular tube,circular annulus and rectangular annulus were carried out,which were abstracted as simple channels to represent the thermal hydraulic characteristics of several Supercritical Water Cooled Reactor（SCWR） fuel assembly design.It was found that,the effect of heat flux,mass flux and pressure on supercritical water heat transfer performance in different simple channels was similar in general.Under the same mass flux and pressure,there was a peak of heat transfer coefficient in pseudo-critical area,which would be decreased with the increasing of heat flux.Under the same heat flux and pressure,the heat transfer coefficient at the same bulk fluid enthalpy would be increased with the increasing of mass flux.The effect of pressure on supercritical water heat transfer performance in different simple channels was not strong except in the pseudo-critical area where the peak of heat transfer coefficient would occur.The heat transfer deterioration phenomenon was also found at different pressures and mass fluxes in different simple channels.