Abstract: In the past forty years,two-phase critical flow has always been an active research subject due to its particular importance in the safety analysis of water cooled nuclar reactors.In this paper,review is made on the two-phase critical homogcneous equilibrium model,slip model,thermal nonequilibrium model and two-fluid model,logether with detailed discussions on the thermal nonequilibrium dynamics rclated to two-fluid model,It is concluded that so far. no numerical model can predict accurately the mass flow ra...