Abstract: Supercritical water-colded reactor (SCWR) is one of the fourth generation nuclear energy systems with the supercritical water as the reactor coolant and moderator. The sharp variation of fluid property near the pseudo-critical point will have influence on the pressure drop characteristics of the flow channel. In this study, the pressure drops due to gravity, acceleration and friction were investigated under supercritical conditions and some suggestions were provided as reference. The flow path integration effect in gravity pressure drop needed to be accounted for. The explicit PKN formula was obtained based on the implicit PKN form which could be applied into isothermal flow. The comparison of different frictional pressure drop correlations with CFD numerical simulation results was made, and it is found that the Kirillov correlation is close to CFD calculation results.