Abstract: The pressure loss component and mechanism of a thermal reverse-flow reactor was analyzed, including the friction losses in the upper and lower headers and in the ceramic bed, and local losses in the intake and exit of ceramic bed. The formulas corresponding pressure losses of each component were established and calculated according to the experimental data. The results show that the local flow losses of inlet and outlet of ceramic bed are much smaller than flow friction losses, and so it could be ignored to simplify the problem. The lower header friction loss is significantly greater than that in upper header and ceramic bed, and most sensitive to the increase of flow rate, and so it occupies the first position in the total loss. The formula to calculate the total pressure loss under different operating conditions is also given in the end.