Scheduling different types of packets, such as real-time and non-real-time data packets, at sensor nodes with resource constraints in Wireless Sensor Networks (WSN) is of vital importance to reduce sensors’ energy consumptions and end-to-end data transmission delays. Most of the existing packet-scheduling mechanisms of WSN use First Come First Served (FCFS), non pre-emptive priority and pre-emptive priority scheduling algorithms. These algorithms incur a high processing overhead and long end-to-end data transmission delay due to the FCFS concept, starvation of high priority real-time data packets due to the transmission of a large data packet in non pre-emptive priority scheduling, starvation of non-real-time data packets due to the probable continuous arrival of real-time data in pre-emptive priority scheduling, and improper allocation of data packets to queues in multilevel queue scheduling algorithms. Moreover, these algorithms are not dynamic to the changing requirements of WSN applications since their scheduling policies are predetermined. In the Advanced Multilevel Priority packet scheduling scheme, each node except those at the last level has three levels of priority queues. According to the priority of the packet and availability of the queue, node will schedule the packet for transmission. Due to separated queue availability, packet transmission delay is reduced. Due to reduction in packet transmission delay, node can goes into sleep mode as soon as possible. And Expired packets are deleted at the particular node at itself before reaching the base station, so that processing burden on the node is reduced. Thus, energy of the node is saved.