Routing protocol in a large scale wireless sensor networks（WSNs） is researched.Long latency of data-transmitting and high energy consumption are main problems of the large-scale wireless sensor networks which is used for gathering data real-time.A multi-priority adaptive（MPA）cluster-based routing protocol is proposed to settle the two problems above.Aimed at different data

multi-priority is adopted and improved TDMA schedule based on the sleep/active nodes pair is introduced.Simulation results show that MPA protocol reduces the time-delay of real-time data transmitting effectively.Besides

it also provides a good energy efficiency to the networks.The MPA protocol is suitable for the large-scale wireless sensor networks.