The invention discloses an electrostatic in-plane MEMS relay, which comprises a substrate and a relay body arranged on the substrate. The relay body includes a support beam having a periodic comb structure, a movable contact provided at one end of the support beam, a static contact provided with respect to the movable contact, and a drive electrode having a comb structure corresponding to the support beam. The driving electrode is arranged to drive the support beam to act under the action of static electricity, thereby driving the moving contact to move, so that the moving contact can contactwith the static contact, and the relay is closed. The performance index of MEMS relay is effectively improved by applying the optimized comb structure to the support beam.