A coupling device includes a plurality of couplers. Each coupler includes a transmission main line and a coupling subline. The transmission main line is used for providing an input end and an output end. The coupling subline is coupled with the transmission main line to provide two coupling ends. The coupling subline includes two first parts located on opposite sides of the transmission main line and a second part connected between the two first parts. The coupling sublines of the plurality of couplers are connected in series to provide a first coupling output port and a second coupling output port. The first part of the coupling subline of at least one of the plurality of couplers has a shared section with the second part of the coupling subline of an adjacent one of the plurality of couplers.