Abstract: In the process of drilling well, the kinematics of drill string is quite complicated. The drill string not only vibrates in longitudinal, transverse and torsional direction, but also random impacts and contacts well wall. Considering random load of drill bit and rock, contact impact of drill string and well wall, nonlinear dynamic model of drill string system coupling longi-tudinal, transverse and torsional vibration is set up, numerical method of parameter of high nonlinear dynamic model is stud-ied, kinematics law, mechanical property of drill string are dis-cussed. This can establish foundation for nonlinear dynamic theory of drill string system coupling vibration in the actual work condition, and has important theory significance and aca-demic value.

Key words: Contact impact, Couple analysis, Drill string, Dynamic, Finite element