By establishing kinematical model of ropeholding motion, knotwinding motion, ropebiting motion of the knotter, timing sequence and position relation of ropeholding, successful knotwinding and accurate ropebiting were described analytically. The effects of the timing sequence difference value φ between the motion of knotting hook and the motion of ropeholding plate and the angle α between the knotting hook axis and principal axis on ropeholding motion, knotwinding motion, ropebiting motion were analyzed. After the ropeloosening, function of ropeholding motion was analyzed. The mechanic condition of firm ropeholding before ropebiting, as well as the mechanic condition of allowing the rope to slip along axle direction of ropeholding plate and avoiding breaking the rope after ropebiting were established respectively. The results showed that the rope could be held firmly, wound successfully and bitten accurately when the value of α and φ are 90° and 24° respectively. The motion test of the physical prototype validated the theoretical model accuracy of ropeholding motion, knotwinding motion and ropebiting motion. The results of knotting test without bundling straws and with bundling wheat straws showed that the knottied rate of knotter may reach 100% and 99.25% respectively, which proved that the motion parameters of the knotter were matched reasonably.