In view of high-speed working characteristics of four-bar beating-up system, the simulation study was carried out under the influence of joint clearance and beating-up resistance. The discontinuous contact model with two-state was applied to clearance modeling of crank bearing. A rigid flexible coupling model of double side four-bar beating-up system was set up by ADAMS/View which on the basis of mechanism design and analysis of beating-up principle. The beating-up resistance from sley was transformed into an equivalent torque on rocking shaft by use of step function. The results of contact dynamics simulation with different clearance states show that there are obvious differences between flexible body simulation and rigid body simulation, and the former can better reflect the real situation of beating-up; The clearance of 0.03 mm and 0.06 mm has a great influence on sley vibration which is not conducive to reduce vibration and noise for loom system; 0.09 mm clearance will not only cause high-frequency reaction force on main shaft bearing, but also aggravate contact and collision between crank and connecting rod; There are many overlaps between centroid trajectory of flexible main shaft with clearance and ideal trajectory, because of that, multi-point contact collision occurs in the crank bearing. The study is helpful to explore mechanical characteristics and working mechanism of the four-bar beating-up system with clearance.