Well Yunxuandi-1， a small-diameter shale gas survey well in eastern Yunnan， was drilled through mainly Cambrian， Devonian， Carboniferous and Permian strata. In the process of drilling， a lot of complex downhole situations were encountered such as severe leakage， fracture leakage， rock breaking and stone falling. To this end， multiple relevant measures， such as drill bit and drilling fluid optimization， combination of various plugging measures， blind drilling， sidetracking， were adopted to solve the problems of severe leakage and block falling caused by large karst caves and longitudinal fractures in massive limestone formation， which avoided wellbore failure caused by excessive drilling fluid density， and improved mechanical efficiency. The drilling experience can provide reference for future drilling of complex limestone strata in eastern Yunnan.