In order to fully use the seismic bearing capacity of sliding piers to improve the seismic performance of continuous bridges，the acceleration activating locking dowel was developed and installed between the piers and beams. To investigate the principal influencing factors on the damping effect of the locking dowel and optimize the damping performance of the locking dowel, taking a seven-span continuous bridge as an example, five test parameters including acceleration activating thresholds, locking clearance, pier height, site condition, and connection stiffness were studied. On the basis of the principle of the orthogonal experiment design, five levels for each factor and twenty-five text schemes were considered. The primary and secondary influencing factors on damping effect were obtained by the extreme difference analysis. Furthermore, the influences of the activating threshold range and connection stiffness on dampingeffect were analyzed. The investigation results indicate that the acceleration of the pier top and the natural vibration period of the pier are closely related, and the acceleration activating thresholds can be determined from the natural vibration period of the pier. Moreover, the damping effect of the device is significantly influenced by the connection stiffness.When the connection stiffness increases, the damping effect is improved.