A novel method for four-bar linkages, that satisfies kinematic design requirements and also attains trade-off of dynamic balance, is presented. By properly designing the speed trajectory of the input link, the disk counterweight of moving links, and link dimensions of the given or desired mechanisms, the expected output motion characteristics and dynamic balancing performance are obtained. The input motion characteristics are designed with Bezier curves. Optimization is applied to find out optimal design parameters for reaching the trade-off of dynamic balance. The input speed trajectory of the input link could be generated by a servomotor. Examples are given to demonstrate the design procedure of this approach.