ing at the problem of slant visibility detection for safe take-off and landing of aircraft, a 4-channel Mie-Raman scattering scanning lidar is developed to achieve the dual-wavelength assumption-free retrieval of the atmospheric extinction coefficient profile, and then to finely obtain atmospheric slant visibility. Based on the atmospheric visibility theory, assuming that there is no light source near the observation path and ignoring the influence of aerosol particle spectrum distribution, the effectiveness of using atmospheric mean extinction coefficient to retrieve slant visibility is analyzed. This lidar utilizes the fundamental frequency (1064 nm) and triple frequency (355 nm) laser pulses of the Nd∶YAG laser as the light source, adopts the Raman polychromator with dichroic mirrors and narrow-band interference filters, and uses the finite state machine theory and multi-thread concurrency technique to realize the multi-module collaborative control software. Combined with the side-scattering visibility meter, the preliminary observation experiments and comparative analysis are carried out. The results show that when the weather is cloudy to overcast, the ground horizontal visibility is 9 km and the pitch angle is 26°, the effective detection distance of this system within 4 min cumulative time is better than 11 km, and the near-ground analysis results are in good agreement.