Abstract: The temperature-programmed desorption (TPD) of hydrocarbons on HZSM-5 zeolite has been investigated. Experimental data showed that only one main desorption peak appeared for n-hexane, cyclohexane and benzene, but for p- and m-xylene there were two desorption peaks. The order of the desorption activation energy obtained is: n-hexane >p-xylene>benzene>cyclohexane. The steam treatment of HZSM-5 at 600°C exerted little influence on TPDof n-hexane, but had a greater effect on TPD of xylene. At low adsorption amount, the molecules of xylene are mainly adsorbed on the less active sites near the entrance of pore channel of HZSM-5. Then they gradually move into the interior of pore channel and occupy the active sites with the increase of the adsorption amount.