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, coefficient 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.