A mechanism by which the number of groups can be reduced in a multi-group P2P network is disclosed. A method for group formation in wireless peer-to-peer (P2P) networks, includes: exchanging group-related information between group owners of neighboring P2P groups; deciding on whether a combined group of the neighboring P2P groups meets a predetermined condition of either of the neighboring P2P groups, based on the group-related information of the neighboring P2P groups; and merging the neighboring P2P groups to form at least one single group when the combined group meets the predetermined condition.