Crossbar network is one of the most important and effective structures to achieve high-speed parallel optical processing in optical switching networks. As a non-blocking network, crossbar network is simple, easy to control, and suitable for forming optical switch matrix. We summarize and analyze crossbar optical switching networks on the recent development for more than 20 years, describe the various crossbar principles, structures and properties of optical switching networks, and analyze the crossbar key technologies for optical switching network.The recent development direction of optical interconnection network is to achieve integrated large-scale optical interconnection. It is predictable that optical interconnection network will become more practical and play an increasingly important role in its application areas.