As most existing enterprise community discovery algorithms focus on homogenous market environment, without reflecting the participation of some enterprises in multiple supply chain operations, a core community representation model based on node mapping relationship, Map-Community, was proposed. By constructing two different role nodes and their different mapping relationships, the ownership community of a enterprise was determined. Based on this representation model, Node Mapping Algorithm (NMA) with approximately-linear time-space complexity was proposed. Firstly, filtering operation was used to obtain the biconnected core graph in the topology diagram of the supply chain network. Secondly, mapping degree was introduced to select the core enterprise nodes. Thirdly, local expansion was performed according to the mapping judgment rules. Finally, the local community structure was extended to the global network by backtracking and overlapping areas were discovered. In the LFR (Lancichinetti-Fortunato-Radicchi) network application experiment, NMA shows low sensitivity to threshold change and is superior to LFM (Local Fitness Maximization), COPRA (Community Overlap PRopagation Algorithm) and GCE (Greedy Clique Expansion) in terms of practicality. Simulation was carried out in the enterprise social network, and the meaning of distribution effect was summarized by the community division. The experimental results verify the feasibility of this algorithm for overlapping enterprise community discovery and its performance advantages in discovery quality.