Abstract: In order to satisfy the omnidirectional laser detection, a structure of lidar based on 2D micro-electro-mechanical systems (MEMS) mirror scanning was proposed. The laser provides light signals to 6 scanning subsystems through a 1×6 high speed optical switch and it realizes 360° horizontal scanning by adding the field of view of 6 scanning subsystems together. The scanning range of each scanning subsystem can reach 60° × 30°, including a transmitting optical antenna that expands the MEMS mirror scanning angle and a large field of view(FOV) receiving optical antenna with gain. The transmitting optical antenna extends the scanning angle of the MEMS mirror from ±10° to ±30°, and the divergence is less than 0.2 mrad. The half image height of the laser echo in the receiving field angle passing through the receiving antenna on the detector is less than 1 mm and the gain of the receiving optical antenna is 3.65. By calculating the corrected lidar equation, the laser beam with a transmitting power of 20 W can achieve an echo power of ≥1 nW within a working distance of 100 m, and the result shows that the optical system can be applied to lidar system.