At home and abroad, serious wellbore instability occurs frequently during drilling in shale formation. In this study, the gas shales are compared with the conventional cap rock, and the water sensitive is analyzed. Unlike the later, the gas shale formation is non-water sensitive as the content of water-sensitive clay, e.g. smectite, in gas shale is seldom. Based on the experimental result obtained by Silurian shale, the stress distribution around the directional well is analyzed. The results show that the trajectory sensitivity analysis for breakout and breakdown mud weights. It can provide a reference for drilling design of shale gas well.