Multi-dimensional multiplexed optical network is the development direction of transmission backbone network, and it promotes the development of network technologies. This paper analyses the key technologies of multi-dimensional multiplexed optical network by investigating the development needs of the information communication network, introduces the research status on space division multiplexing technology at physical transmission level, and explains cutting-edge technologies with typical significance in the architecture, spectrum allocation and spectrum reconstruction of multi-dimensional multiplexed optical networks. Finally, the development direction of multi-dimensional multiplexed optical network and its cutting-edge technology are prospected.