Clay invasion is the phenomenon that formation clay invades drilling fluid, leading to performance deterioration of it. As long as drilling in the sedimentary strata (usually sandstone, mudstone, shale and limestone), there is more or less drilling fluid invasion problems caused by clay, which result is drilling fluid performance deterioration. The stratum mud making solved the clay invasion problem and varied harm into use. The key problem is what kind of formation can be used to make mud. Currently there are involuntary uses of stratum mud making in various places in China, while little specific study on mud making is made. The paper discussed the study on stratum mud making with the case of ZK012 census hole in the rock salt potash mine district of Suxiang, Mingguang.