The invention relates to the technical field of gearboxes for automobile accessories, in particular to an automatic detecting and press-fitting device for an automobile accessory gearbox. The automatic detecting and press-fitting device comprises a base frame, a worktable, a guide rail, a bottom plate, a die seat, a fixing plate, a supporting frame, a lifting air cylinder, a pressing plate, a detection display, a pressure-resisting detector, a sealing detector and a controller. During use, the gearbox is firstly put on the die seat, and a shaft sleeve is arranged in a device hole of a pressing block; afterwards, the bottom plate and the die seat move to the position below the pressing plate, and then the lifting air cylinder is driven to descend downwards to press the pressing block so that the shaft sleeve can be pressed into a connecting hole of a base; and meanwhile, the pressure-resisting detector is used for conducting pressure-resisting detection on the base, a sleeve and a connecting seat, and sealing detection is conducted on the sleeve through the sealing detector. Thus, shaft sleeve press-fitting and pressure-resisting and sealing detection can be automatically completed at a time, in addition, the press-fitting quality is good, detection is accurate, operation is simple, and the work efficiency is high.