Abstract: Based on the characteristics of the wireless sensor networks, a real-time routing protocol was proposed. The protocol provided a predictable upper bound for the end-to-end delivery delay. The real-time end-to-end guarantee was achieved by geographic forwarding, periodic message exchange between neighbor nodes, and stateless one-hop delay guarantee. If congestion appears, back-off rerouting is adopted. This method can be adaptive to network congestion. Experimental results show that the real-time routing protocol is correct and efficient. It can be used for real-time sensor network applications.