The principle of optical phased array is briefly discussed. The development of optical phased array is reviewed, especially the research progress of silicon photon phased array in recent years. Large-scale integration has been achieved by using silicon-on-insulator (SOI) technology compatible with complementary metal oxide semiconductor (CMOS) process lines. And the largest silicon photon phased array has been reported abroad, and its size is up to 4096 elements. The two-dimensional beam scanning angle achieved on silicon photons can reach 46°×36°, the beam width is only 0.85°×0.18°, the antenna loss is less than 3 dB, and the sidelobe suppression is greater than 10 dB. In addition, the steering speed of the optical phased array made of micro-electromechanical system (MEMS) devices is more than 0.5 MHz. Advantages and disadvantages of various methods to realize optical phased array are expounded, and the future development prospect is prospected. Finally, the applications of optical phased array in laser radar, imaging and military are introduced.