The invention relates to an etching cleaning method of LBO crystals, and belongs to the technical field of laser. The method is a repeated-iteration method of polishing, chemical etching, cleaning drying, ion beam etching, secondary polishing and secondary chemical etching. According to anisotropism and material surface micro deliquescence characteristics of the LBO crystals, the specific polishing, etching and aftertreatment process is adopted, the iterative technology between different steps is adopted so as to effectively remove new defects and procedure residues of the previous working procedure, and the high-quality LBO crystal surface with the low sub surface damage layer and the low surface roughness is finally obtained. Compared with the prior art, the method has the beneficial effects of being high in process pertinence, obvious in effect and the like and is suitable for improvement of laser damage resistance performance of low-deliquescence crystal materials.