An inexpensive satellite receiver can receive high bandwidth traffic from a satellite, while no bandwidth from the receiver to the satellite is provided. Therefore the connection between the satellite and the satellite receiver is unidirectional. The existing routing protocols stand on the fact that any links are bi-directional. They can not handle unidirectional links. Some scholars use a tunneling method to solve this problem, but the tunneling method needs a fixed back channel from satellite receiver to the satellite uplink station. It can not adapt to dynamic topology change. In this paper, the authors propose a dynamic routing algorithm that can be applied to networks with unidirectional links. The routing algorithm can also adapt to the change of network topology.