Abstract: With the development of opticalfiber communications, the function of optical switches is becoming increasingly prominent since they serve as kernel devices for optical add-drop multiplexing（OADM）and optical cross connecting（OXC）. This article classifies optical waveguide switches from three different angles: unit structure, material and modulating mechanism. We also discuss the basic principles and latest developments of waveguide switches, and analyze the technological challenges with comments from our point of view.