The adsorption step play an important role in zeolites catalysis reactions.Using molecular simulation methods can not only get some adsorption properties as experiment methods,but also can get more microcosmic informations.The adsorption properties of linear C2-C8 alkanes and olefins on H-FAU zeolites were studied by the DFT-D(PBE/dnp3.5/Grimme)method in a 84T cluster.The total adsorption energy is consist of DFT calculation energies(represent mainly the interactions between adsorbates and Br(o)nsted acid sites of zeolites)and Dispersive correction energies(represent mainly the interactions between adsorbates and zeolites framework).The DFT-D calculation results indicate that adsorption energies of alkanes and olefins on H-FAU zeolites increase with an increase in the number of carbon atoms,and the amount of increase is approximately constant;In the same carbon number,the trend of adsorption energies is 2-alkenes>1-alkenes>alkanes; Interactions of olefins double bond with Br(o)nsted acid sites of zeolites lead to the higher adsorption energies of olefins than alkanes; The adsorption energies of 2-alkenes are higher than 1-alkenes are both because the stronger interactions of 2-alkenes double bond with Br(o)nsted acid sites of zeolites and the stronger dispersive interactions between 2-alkenes and zeolites framework.The mechanism of the interactions of olefins double bond with Br(o)nsted acid sites of zeolites is that the π-electrons of double bonds transfer from the HOMO of olefins to the LUMO of zeolites,the electrons transfer leads to the formation of a second bond between the hydrogen atom of hrdroxy in zeolites and the double bond of olefins.Alkanes does not have π-electrons,the hydrogen atom of hrdroxy in zeolite can only get σ-eletrons from the alkanes which is less than the π-electrons transfer.These findings can explain that olefins are more easily to be protonized than alkanes after adsorption on the Br(o)nsted acid sites of zeolites,which means that the olefins have higher ractivity after adsorption on H-FAU zeolites.