The invention discloses a method for allocating resource including: a base station calculating a number of PDCCH aggregation degree groups based on CCE resources which can be occupied by PDCCH in a subframe, wherein PDCCH aggregation degree groups are divided based on a largest PDCCH aggregation degree; the base station setting at least one aggregation degree group in the middle of the total PDCCH aggregation degree groups as a common search space; and the base station, based on UE information and common information, determining PDCCH aggregation degree groups which are set as a UE specified search space using a space division function; and the base station searching a location of the UE specified search space in determined PDCCH aggregation degree groups which are set as the UE specified search space and performing PDCCH resource allocation. The invention ensures unity of group numbers of selectable aggregation degree groups among aggregation degree groups which are divided based on the largest aggregation degree, achieves simplification of allocation modes and improves efficiency of PDCCH resource allocation.