The field of view of UAVs varies greatly during large maneuvering movements， and visual features are easily lost in weak texture environments， which greatly reduces the accuracy of visual ranging. To address this problem， this paper combined a catadioptric omnidirectional camera with structured light， and further proposed a catadioptric omnidirectional monocular visual ranging method with fused structured light. In this study， in order to improve the accuracy of the ranging method as well as the processing speed， the region of interest （ROI） of the structured light was first extracted and the median filter was applied to denoise the laser streak image， and then the improved Steger algorithm was used for the extraction of the center coordinate of the structured light streak at the sub-pixel level. Second， the least squares principle was applied to curve-fit the extracted sub-pixel points to obtain the curve equation of the structured light. Finally， the spatial plane parameters were derived through theoretical derivation to establish the ranging objective function to further obtain the distance information.In different scenarios， the ranging accuracy of the proposed ranging method is within 3%， which proves the effectiveness of the method.It meets the demand for stable and reliable ranging of UAVs under large maneuvering conditions and weak texture scenes， and further improves the ability of UAVs to perceive the environment.