Three R bar group as a typical mechanism of a linkage is studied. Analysis method is based on the theory of kinematics and the method of mathematics. After deriving of relevant kinematic equations, detail analysis about positions, velocities, accelerations, and angles, angular velocities, angular accelerations of bars as well as other kinematics parameters of three R bar group to be searched can be obtained in the paper. Relationships between known and unknown parameters of three R bar group have been determined according to different working states of three R bar group. The method presented in the paper provides a feasible and more efficient method for the analysis of kinematic characteristics of plane linkages.