Up to now, optical phased array (OPA) technology has been developed for more than 70 years. According to different applications, a variety of devices and techniques have been developed, such as liquid crystal, MEMS, optical waveguide, coherent beam combination and so on. Optical phased array technology has been applied in laser radar, space optical communication, high brightness laser generation, synthetic aperture detection and other application fields. By controlling the phase of sub-beam in the beam array, the phase plane of the array beam can be reconstructed and accurately controlled with the optical phased array technology, which has the advantages of small volume and weight, fast response speed and good beam quality. In this paper, the principle of optical phased array was firstly introduced. Secondly, the development status, application areas and development trend of several main techniques were reviewed from two aspects of laser emission and long-distance imaging. Finally, some thoughts and suggestions were given.