Abstract: During the process of pilot hole drilling and reaming of directional drilling, the drill rod often breaks off due to fatigue damage. In the case of the absence of relevant regulatory requirements, the authors established a drilling string-hole whole hole model with large finite element software ABAQUS for an ultra-long directional drilling project, and performed finite element analysis for stress states under two working conditions, that is, pilot hole drilling and reaming, through comprehensive consideration of the drilling string service environment, friction collision of rock and soil to drill string, and flotation of mud, etc., and carried out safety evaluation of drill rod. The simulation results show that the pilot hole drilling of super-long directional drilling is suited to the use of opposite crossing technology. If the drill rod has been used for more than 288 h in directional drilling and reaming process, it should be replaced. Performing stress analysis for drill pipe with finite element method can effectively guide directional drilling construction.