The distribution characteristics of nonlinear hydrodynamic force in deep hole drilling system were studied.The governing equation of the nonlinear hydrodynamic force was solved by using the finite difference method.The effects of eccentricity,the ratio of length to diameter,whirling velocity and vibration velocity on the distribution of nonlinear hydrodynamic force were discussed.The results show that the nonlinear hydrodynamic force is increased with the increasing of eccentricity,but its change is not obvious with the increasing of the ratio of length to diameter,especially for large ratio of length to diameter.With the increasing of the positive whirling velocity,the nonlinear force in the convergence zone is increased,while the nonlinear force in the divergence zone is decreased.The influence law of the reverse whirling velocity on the nonlinear force is just opposite to that of the positive whirling velocity.The nonlinear fluid force is increased with the increasing of the positive vibration velocity and decreased with the increasing of the positive vibration velocity.In addition,the extreme value of the pressure at the minimum clearance occurs due to the change of the vibration velocity,which leads to disappearance of antisymmetry characteristics of the pressure distribution in the convergence and divergence zone.