Abstract: A three-dimensional drill stem dynamics analysis model is established in accordance with the integrated drill stem in horizontal well, and a dynamics equation describing drill stem vibration in hole space is also created by three-dimensional dynamics finite element method. A computer program on drill stem vibration analysis and fatigue critical stress analysis is developed using PASCAL, and it proves to be practical through analyzing the planed borehole data and actual measured data of the first sidetracked horizontal well in Daqing, Gao160-CP38. This study will be good for the development of sidetracked horizontal drilling in Daqing and other oilfields.