In hydro-geological drilling, the influence of drilling fluid on aquifer clogging and water yield of the aquifer has been the problem that we care about. The thin and tough mud cakes, which are formed by the high quality drilling fluid, are good for well washing with high performance. In the drilling process, high quality drilling fluid can quickly form mud cake on the borehole wall. This in turn prevents free water from invading into the pore channels of the aquifer. So that solid phase diffusion radius is small and water yield is high. It is good for the evaluation of hydro-geological parameters. When conditions permit, the hydro-geological drilling fluids can be ranked according to following order of priority: low density washing medium, solid free drilling fluid, coarse dispersion drilling fluid, fine dispersion drilling fluid and water. This paper briefly introduces the requirements, type selection and performance index control of the drilling fluid used for hydro-geological drilling, and we hope to provide some reference for the use and management of the drilling fluid in the hydro-geological drilling.