Abstract: Aiming at the problems of unreliable wireless communication data transmission and low network lifetime in smart distribution network(SDN), a multi-path QoS routing algorithm(MQRA) for wireless sensor networks(WSNs) based on improved harmony search is proposed. Firstly, the data transmission model is established by analyzing the communication requirements of the distribution network. Then, the harmony search(HS) algorithm is improved according to the characteristics of the wireless sensor routing problem. The adaptive parameter formula is improved to avoid the algorithm falling into local optimum. By constructing a forward region between the source node and the destination node, the forwarding node set is optimized to avoid data backhaul and improve the efficiency of the algorithm. Finally, in the initial harmony library generation stage, the probability formula in the disk method is improved by considering the distance, packet loss rate and node residual energy. The simulation results show that the MQRA algorithm can effectively reduce the delay of data transmission, improve data reliability and balance node energy consumption to extend the network lifetime.