Reliable downlink transmissions from the sink to actuators for control data in Industrial Wireless Sensor and Actuator Networks (IWSANs) are extremely important for industrial control applications. However, on the network layer, existing routing protocols fail to fully support downlink transmissions for actuators, due to the insufficiency of reliability, robustness and real-time performance. In this paper, we propose a reliable flooding-based routing scheme focusing on downlink transmissions. Packets are forwarded to actuators according to weight values and the related node lists in intermediate nodes. Performance evaluations via simulations show that our protocol significantly outperforms traditional routing protocols in terms of reliability, transmission latency, network recovery time and network resource usage. © 2013 IEEE.