Mis-assembly prevention device

The utility model discloses a mis-assembly prevention device comprising two electromagnetic sensors placed above to-be-detected parts of a to-be-assembled member I and a to-be-assembled member II. The mis-assembly prevention device also comprises a work piece position electromagnetic sensor which sends detection signals to the electromagnetic sensors when the to-be-assembled member I and the to-be-assembled member II are moved to detection positions along with an assembly line tool plate. The electromagnetic sensors are connected with an audible and visual alarm. The audible and visual alarm gives alarm when the signals of the two electromagnetic sensors are not detected simultaneously in the process from reception of the signals to the disappearing of the signals of the work piece position electromagnetic sensor. With the method, the mis-assembly prevention device can prevent mis-assembly of parts which are symmetrical from left to right and can give audible and visual alarm automatically under the condition