In order to evaluate and analyze the stratum fragmentizing situation in Yemaquan mining area of Qinghai, 6 evaluation indexes are put forward: broken specific surface, broken block, porosity of rocks, rock disintegration rate, coeffi- cient of rock integrity, compressive strength of rock. The fragmentized stratum classification standard is established by using fuzzy mathematical evaluation system and combining with rock fragmentized degree index; and combined with the drilling site situation of Yemaquan mining area, the fragmentized stratum is divided into 5 categories. A targeted drilling fluid system is studied out for fragmentizing stratum.