The invention relates to the technical field of intelligent mainboard machining auxiliary devices, in particular to a smoke processing unit for intelligent mainboard welding. The smoke processing unitcan timely and sufficiently suck away smoke generated in the welding process, and injurious ingredients in the smoke can be processed more sufficiently; and meanwhile, noise generated in the runningprocess of an axial flow fan can be effectively reduced; the smoke processing unit comprises the axial flow fan, a box, an activated carbon filtering net, a high altitude exhaust pipe, a rectangular tube, an operation table, a left support plate, a right support plate and a plurality of sets of smoke sucking cover devices; and each smoke sucking cover device comprises a transverse sliding plate, acover body, a lifting plate, two sets of threaded pipes, two sets of threaded rods, a communication air pipe and an upper ball bearing, and further comprises a circulating box, a spraying pump, a gear motor, an upper spraying pipe, a lower spraying pipe, a backflow pipe, a left ball bearing, a right ball bearing, an upper spraying branched pipe, a lower spraying branched pipe, a driven gear, a rotating shaft, a semi-gear, a front noise reduction clamping plate, a back noise reduction clamping plate, a front fixing plate, a back fixing plate, a front clamping spring and a back clamping spring.