Geostress monitoring holes function as the base of geostress measurement and monitoring； thus， the drilling quality directly affects the effect of geostress measurement， and the reaming quality is the key factor to decide whether the geostress monitoring instrument can be installed smoothly and whether the monitoring instrument can work normally. Great attention should be paid to the drilling work of geostress monitoring holes， and research on drilling technology for geostress monitoring holes should be strengthened. Taking the drilling of a geostress monitoring hole in the Beijing-Tianjin-Hebei Collaborative Development Region as an example， this paper introduces the drilling technology for geostress monitoring holes in detail， including configuration of the core drilling string， selection of the diamond bit， step reaming with the modular reaming bit； and it also proposes some concrete measures to ensure the verticality and concentricity of monitoring holes， reduce the error in hole diameter， ensure core recovery， and improve reaming efficiency and quality， which have led to good drilling results. They can provide important guide for drilling of the geostress monitoring hole in the future.