The invention discloses an oblique type bridge anti-seismic damper and a parameter optimization method thereof, and relates to the technical field of bridge seismic resistance. The parameter optimization method comprises the following steps: establishing a bridge dynamic finite element model, calculating and obtaining a horizontal seismic dynamic response result and a longitudinal seismic dynamic response result of a bridge; optimizing a horizontal equivalent damping coefficient Ct, a longitudinal equivalent damping coefficient C1 and a speed index alpha of the oblique type bridge anti-seismic damper; calculating an oblique included angle beta and a damping parameter C of the oblique type bridge anti-seismic damper; and outputting the equivalent damping coefficient Ct, the longitudinal equivalent damping coefficient C1, the speed index alpha, the damping parameter C and the oblique included angle beta which satisfy the practical bridge design requirement. According to the oblique type bridge anti-seismic damper and the parameter optimization method thereof provided by the invention, when the bridge has a horizontal seismic action and a longitudinal seismic action, the oblique type bridge anti-seismic damper can play a role in damping energy dissipation, so that an effect of using only one set of oblique type bridge anti-seismic damper to control the longitudinal and horizontal seismic actions synchronously can be achieved.