In order to solve the problem of positioning in UAV flight and landing guidance scene, this paper presented a ranging and positioning method based on wireless ultraviolet lights. The method analyzed communication models of wireless ultraviolet Line of Sight(LOS) and Non-Line-of-Sight(NLOS), thus deriving the distance algorithm for LOS and NLOS communications. The location coordinates of unknown nodes were solved by the four node localization algorithm. Using a 255 nm UV LED as the light source, a PMT as the receiving device and a 10 kHz square wave signal as the ranging signal, ranging experiments under different weather conditions were performed. The experimental results indicate that the ranging error is less than 5 m in LOS communication with the ranging distance of 0~100 m. In NLOS communication, the effective ranging distance is reduced to 0~70 m due to the influence of multipath scattering. When the transmitting elevation and receiving elevation is less than 10°, the ranging error is less than 5 m, otherwise the effective distance decreased significantly with the increase of transmitting and receiving elevations. In general, the algorithm can provide navigation data for unmanned aerial vehicles with a high accuracy when the GPS cannot work normally, thus can meet the requirements of autonomous landing and flight guidance.