Embodiments of the present invention include a method for performing cell reselection in a mobile communication system. The method comprises the steps of reading, by a user equipment (UE), the Access Class (AC) barring parameters of the serving cell which are broadcast from a base station, and performing an AC barring check; calculating the cell reselection values of the serving cell and the adjacent cells according to the cell reselection parameters broadcast by the base station when the AC barring check fails; and ranking the calculated cell reselection values, selecting by the UE the cell corresponding to the maximum value of the calculated cell reselection values as the serving cell of the UE.