In order to solve the problems of large volume and complex structure of traditional aerosol light detection and ranging (LiDAR), a compact portable micro pulse LiDAR system was proposed. The aspheric lens optical transceiver system was designed by using the optical structure of coaxial transceiver. The stray light was analyzed, and the influence of stray light was reduced through the structural design. Theoretical analysis and experimental verification were carried out, and aerosol detection data after reducing the influence of stray light were obtained. The results show that, the range resolution of the developed radar system is 6 m, and the aerosol distribution within 3 km can be detected in real time. This study provides a reference for the miniaturization of micro pulse LiDAR equipment.