Abstract: The experiment of post-dryout transition boiling heat transfer in rectangular channel has been carried out on the basic experimental loop of flow and heat transfer.The characteristics of the transition boiling heat transfer is analyzed.The effects of thermal-hydraulic parameters such as inlet quality,mass flow velocity,and system pressure on the characteristics of post-dryout transition boiling heat transfer are experimentally researched.The results show that the post-dryout transition boiling is unstable,wall temperature oscillates fiercely,and the mass flow velocity and pressure drop oscillate as also;the post-dryout transition boiling heat flux and heat transfer coefficient are decreased,but the wall temperature is increased with the increasing of inlet quality;and the post-dryout transition boiling heat flux and heat transfer coefficient are increased,but the wall temperature is decreased with the increasing of mass flow velocity or system pressure.