Abstract:The paper discussed and analyzed an important parameter—build-up intensity (the drift angle’s change of drilling hole in one meter length drilling, degree/meter) which influences the hole section designed. It has established the build-up intensity model through the whole stress analysis on drilling tool and has obtained the formula of build-up intensity affected by the resistance of soil and the curve of drilling tool in the preliminary stage of angle building. Then it analyzes the primary factors that affect the buildup intensity in the basis of formula and has got some conclusions. This paper also gives qualitative explanation on the rule of continuous buildup intensity by indoor tests.