A lens-cleaning device for cleaning dust deposited on a plurality of lenses, includes a tray, a front cover, and a plurality of air nozzles. The tray defines a plurality of grooves and a plurality of through holes alternately arranged in a first surface of the tray. Each of the lenses is received in one groove. The front cover defines a plurality of assembling holes in a second surface of the front cover corresponding to the through holes. The front cover covers the tray with each of the air nozzles received in one assembling hole, and the air nozzles are capable of blowing air against the lenses causing the dust deposited on the outer surface of the lenses to be blown away through the through holes.