Abstract: Based on the structural and operational characteristics of the China Advanced Research Reactor（CARR）,a thermal-hydraulic and safety analysis code was developed with the consideration of all possible coolant flow and heat transfer status.The code was adopted to analyze the severe station blackout accident（SBO） with the failure of both the control rod（CR） and the Emergency Core Cooling System（ECCS）.Some important thermal-hydraulic parameters,such as pressure,flow rate and temperature,in the mean channel and hot channel were obtained.The computational results indicated that the core power could decay to a very low level with the reactivity feedback of the coolant density,void fraction and fuel temperature,thus the integrality of the fuel assembly/element could be ensured under such sever accident condition.The results also showed the high inherent safety of the CARR.Furthermore,an interesting short-lived density wave flow instability phenomena occurred during the transient process.