The invention discloses a mosquito repelling device used for a pig farm. The device comprises a supporting rod. The top part and the bottom part of a left side surface of the supporting rod are respectively fixedly connected with a first cross bar and a second cross bar. Opposite surfaces of the first cross bar and the second cross bar are clamped with bearings, and inner surfaces of the two bearings are coupled with a same rotating shaft. The top end of the rotating shaft is fixedly connected with a connecting rod. The mosquito repelling device used for a pig farm makes teeth mesh with a gearintermittently, so that a repelling net swings backward around the rotating shaft. When the teeth are not meshed with the gear, the repelling net swings forward and a motor continuously rotates, so the repelling net swings forward and backward in a reciprocating manner around the rotating shaft, to repel mosquitoes. Mosquitoes cannot stay above the pig farm, biting of mosquitoes on pigs is prevented without using pharmaceuticals, and pathogen infection of pigs caused by mosquito bites is prevented, so that the device brings about convenience for farmers, and is beneficial for breeding of thefarmers.