Abstract: The laboratory inspection and analysis was carried out on the fracture of drill pipe body of extended reach well in the East China Sea. The drill pipe fracture belongs to fatigue overload fracture. Combined with the actual operation of the well, the drill string mechanics finite element simulation analysis was carried out. The results show that the drill pipe material meets the relevant standards. The local serious "dogleg" caused by the wellbore instability is an important factor to accelerate the fatigue failure of drilling tools. Some suggestions for the drilling design and the use management of drilling tools for extended reach wells are given, which can effectively guide the follow-up drilling operations for extended reach wells.