Abstract: To understand heat transfer mechanism from general character and make clear the difference caused by properties, experiments of heat transfer to water and Freon R134a flowing upward in vertical tubes were conducted on SWAMUP and SMOTH test facilities, respectively. The variations of heat transfer coefficients of water and Freon with dimensionless temperature are coincident in the case of normal heat transfer, heat transfer enhancement and heat transfer deterioration due to buoyancy force and acceleration effect. The HTC ratio decreases with the increase of dimensionless parameter _πB. The HTC ratio increases first and then decreases with the increase of dimensionless parameters _πA. The dimensionless parameters _πB and _πA show better relevance on the supercritical water and Freon experimental data, respectively. The investigation of the heat transfer behavior of supercritical water in the SCWRs by means of model fluid Freon R134a is proved reasonable and feasible because of the similarity dependence on dimensionless parameters.