Research and development of Terahertz (THz) devices based on liquid crystal technology have been one of the important research directions in the area of THz technology. The application background and basic knowledge of THz liquid crystal device are introduced. The electro-optical and material properties of liquid crystal in the area of THz are discussed in detail. Some potential liquid crystal materials are introduced. Based on this, the design principle and presented research results of THz liquid crystal phase shifter, THz tunable liquid crystal filter and THz tunable polarizer are analyzed. The application developments of THz liquid crystal devices are summarized and analyzed finally. And research and development directions of the devices are proposed.