Abstract: In order to improve the precision of the reactor core flow distribution, the CFX code was used to simulate the three-dimensional flow through type-1 throttle structure, throttle structure and flow 1 zone pin in China Experimental Fast Reactor based on standard k-ε turbulence model and SIMPLE algorithm. The effect of the wall surface of the material on the pressure drop was taken into account during the simulation process in order to further approach the real situation in the experiment. The gravity pressure drop and pressure drop along the path as well as the local pressure drop were regarded as experimental system error correction when the numerical results were compared with the available experimental results. The results show that the simulation results and experimental results after reasonable correction are in good agreement. The average outlet flow in pin 1, 5 and 6 is 3.8% lower than the average outlet flow in pin 2, 3, 4 and 7. Not only the flow distribution in the hottest tube can be more accurately determined, but also the reference for the future hydraulic bench test is figured out according to the simulation results.