In order to study the competitive adsorption relationship between sulfides in the adsorption desulfurization (ADS) process, as the loads increase gradually to saturation adsorption, the competitive adsorption mechanism of thiophene /diethyl sulfide on the all-silicon Y zeolite was investigated by GCMC simulation for the first time. A two-stage loads dependence adsorption mechanism was acquired which can be named ‘‘optimization-displacement adsorption” and “relocation-displacement adsorption” with an inflection point of 36 molecule/UC. At the ‘‘optimization-displacement adsorption” stage, both thiophene and diethyl sulfide molecules could occupy the optimization adsorption site ideally in the initial phase and the thiophene molecules on the S sites (refers to other sites except for W sites in the supercages) would be displaced by the diethyl sulfide ones and migrated to the W (refers to the 12-members ring connecting the supercages site) when the total loads approached the inflection point. At “relocation-displacement adsorption”, the thiophene molecules on the S site would be displaced by the diethyl sulfide ones and migrated to the W sites sequentially. Meanwhile, more and more proportions of the latter diethyl sulfide molecules are adsorbed away from the center of the supercage. This transformation of the competitive adsorption mechanism was proved to be related to the interaction energy. Besides, three more realistic factors on the adsorption behavior were investigated respectively. It was concluded that high temperature is conducive to enhancing the selectivity of thiophene adsorption, but lower temperature can remove the sulfide more completely. Cations may improve the selectivity of sulfide ether. Besides, mercaptan has a great effect on the adsorption of other sulfides.