Abstract: An ant routing algorithm based on a lightweight hierarchical structure was proposed to address problems related to mobile nodes, dynamic topology, limited resources, and inadequate scalability over mobile peer-to-peer (P2P) networks. In this algorithm the network was divided into lightweight hierarchical structures by selecting nodes on active routers and running the ant routing algorithm on these structures. The lightweight hierarchical structure improves efficiency of the pheromone update mechanism of the ant algorithm. In addition, the self-organization and load-balancing properties of the ant routing algorithm increases the robustness of the lightweight hierarchical structure. Simulation experiments demonstrated the effectiveness of the algorithm.