Aiming at the problem of increasing investment cost of knotter production due to difficulty in evaluation of good or bad design after structure improvement or parameters adjustment of the knotter, a kind of virtual knotting method of knotter based on rigidflexible contact dynamics was presented according to the judgment rule of whether the knotter could tie a knot during design phase. The method used the Bushing connection tool under ADAMS to build up dynamic model of flexible rope with large deformation. A complete virtual knotting simulation process of the knotter was implemented by setting up multiple contact constraint between the rope and rigid component of the knotter and applying load to the rope. Rigidflexible interactive mechanical behaviors of tying a knot of the knotter were studied under the action of pulling force of the rope. The comparison analyses between knotting movements of the knotter prototype and virtual knotting results validated the correctness of dynamic model of the rope and simulation model of rigidflexible contact dynamics. It may be regarded as an effective method to evaluate good or bad design and guarantee disposable successful production of the knotter. The effects of the timing sequence difference value φ between the motion of knotting hook and the motion of ropeholding plate on knotting motion of the knotter were analyzed by using the proposed virtual knotting method, which can play visual validation role to judge whether the knotter can knot or tie a good and bad knot after parameters match of the knotter.