Delay requirement becomes a key problem in sensor networks in the time-critical applications. This paper proposes a real-time routing protocol in sensor networks. A novel concept of Effective Transmission (ET) is put forward to ensure each forwarding node is farther from the source node and nearer to the destination node with respect to its sender. The end-to-end delay requirement is separated into the sum of point-to-point Constrained Equivalent Delay (CED). Each intermediate node can independently decide its next forwarding node according to each CED, so it will greatly simplify the route discovery process. The simulation results show the routing protocol is effective on the performance of energy consumption and end-to-end delay compared with some other routing protocols.