To expand network coverage and enhance the reliability of wireless personal area network (WPAN), the problem of address overflow resulting from applying the meshed adaptive tree algorithm in largescale mesh network wis studied. By dividing the entire network into smaller subnetworks, the subarea meshed adaptive tree wis constructed. An improved meshed adaptive tree routing algorithm wis proposed employing the hierarchical topology structure of the subarea meshed adaptive tree. Experimental results show that the algorithm expands the network coverage without increasing the routing overhead and the network load. It also effectively reduces the endtoend delay and increases the packet delivery ratio and communication efficiency. It maintains a good performance in the networks with different scales and provides a theoretical basis for enhancing the coverage and reliability of WPAN.