A set of counter-balanced dither mechanism for Ring Laser Gyroscope (RLG) has been designed to reduce the influence of lock-in of RLG. Designed dither frequency is 344.16Hz. By Finite Element Methodology (FEM) calculation, it js proved that the mechanism mode is reasonable and the strength requirements of the mechanism's material are satisfied. The error between the actual dither frequency, 316Hz, and the designed is less than 8.2%. In 30 minutes, the stability of dither frequency and amplitude (RMS value) are less than 0.05% and 5% respectively. The horizontal direction of the mechanism is much easier to be influenced by base vibration than the vertical one, but the readout signal is still good for application.