A coating device includes a rotatable base, a board for holding workpieces, a positioning shaft positioned on the rotatable base, two eccentric wheels, a rack, and two reciprocating shafts. The two eccentric wheels are fixed on the positioning shaft and extend from the positioning shaft along two opposite directions. The two eccentric wheels are parallel to and spaced from each other. The rack is rotatably connected to the rotatable base. The rack is capable of rotating around the positioning shaft. Each reciprocating shaft is positioned on the rack. Each reciprocating shaft includes a hinge portion rotatably connected to an end of the board and a sliding portion slidably connected to the edge of a corresponding eccentric wheel. The two eccentric wheels are capable of driving the two reciprocating shafts to move alternately toward and away from the positioning shaft along radial directions of the positioning shaft.