The invention discloses an online bottle missing detection device for beer boxing, which comprises an industrial camera, an optoelectronic switch, an industrial control computer, and a manipulator, wherein the industrial camera, the optoelectronic switch and the manipulator are all connected with the industrial control computer, and the industrial control computer is connected with an assembly line; when a beer box on the assembly line reaches the optoelectronic switch, signals of the optoelectronic switch are received by a built-in program of the industrial control computer, the built-in program of the industrial control computer triggers the industrial camera arranged right above the beer box to take a photo, the built-in program of the industrial control computer carries out bottle missing identification on the taken beer box photo, if bottle missing is identified in the beer box, the manipulator is triggered to execute a relevant action; and the relevant action executed by the manipulator is to push the beer box to a rotating branch line of the assembly line, and the beer box is returned to the starting place of the assembly line for bottle filling. The online bottle missing detection device for beer boxing has the beneficial effects that online detection on the beer boxing bottle missing is realized by using the optoelectronic switch, the manipulator and an industrial machine vision technology, and the working efficiency can be improved.