To investigate the inhibition mechanism of KHCO₃ inhibitor on polypropylene/propylene two-phase explosion, the inhibition mechanism was analyzed from both physical and chemical aspects by examining flame propagation characteristics, pyrolysis characteristics and chemical reaction kinetic mechanism, revealing the interruption of the explosion reaction process. The results show that KHCO₃ exhibits an inhibitory effect on polypropylene/propylene two-phase explosions with different concentration ratios. KHCO₃ decomposes under heating and absorbs a large amount of heat, and the carbonate produced by decomposition adheres to the surface of PP dust, raising the melting point of PP dust from 160 ℃ to 222 ℃. Meanwhile, the maximum consumption rate of ·H by the reaction KOH + H \underset{}{\rightleftharpoons } K + H₂O reaches the highest value of -0.007 45 mol/(cm³·s). The maximum consumption rate of ·OH by the reaction KOH + OH \underset{}{\rightleftharpoons } KO + H₂O reaches the highest value of -0.011 34 mol/(cm³·s). At high temperatures, KHCO₃ generates gaseous K and KOH at the flame front, which continuously scavenge ·H and ·OH through the K \underset{}{\rightleftharpoons } KOH cycle and convert them into H₂O, thereby achieving explosion suppression.