Abstract: The intrinsic deposition rate of pyrolytic carbon from propylene was studied using a chemical vapor infiltration hot wall reactor at partial pressures of propylene from 3 kPa to 7 kPa, temperatures of 1 173 to 1 273 K, and a residence time of 1.1 s. The effect of the partial pressure of hydrogen on carbon deposition rate at different temperatures was studied at constant propylene partial pressures. A model of the deposition mechanism of propylene was established. The results show that the propylene deposition rate increases with increasing partial pressure, increased distance along the path and increasing temperature. Hydrogen inhibits the deposition. The deposition mechanism model shows that the reciprocal of the propylene deposition rate is linear with the reciprocal of the propylene concentration, and the reciprocal of the propylene deposition rate is linear with the hydrogen concentration. Comparing the experimental results of propylene deposition rate, the rationality of the model is proved and the kinetic parameters are calculated.