The periodic and dynamic topology of satellite networks poses new challenge to the design of routing protocols. Since the routing protocols of conventional networks can not be effectively applied to satellite networks, many new routing techniques for satellite networks were put forward. With an introduction to satellite network architecture and topology control strategies along with the developmental history of routing techniques on satellite networks, this paper summarizes the core mechanism, feature and major problems of some important routing techniques of satellite networks from the classification perspective. Considering application requirements, the paper also suggests the future trends towards the development of routing techniques on satellite networks.