The invention discloses an overturning stopper adding and capping device for a linear plastic bottle filling sealing machine. The overturning stopper adding and capping device comprises a feeding mechanism provided with a feeding groove, a material dividing mechanism in butt joint with the feeding mechanism, a clamping mechanism in butt joint with the material dividing mechanism, and a positioning mechanism corresponding to the clamping mechanism. The material dividing mechanism comprises a separation baffle movably arranged at the end of the feeding groove and moving in a reciprocating mode relative to the feeding groove. The separation baffle is provided with a notch corresponding to the feeding groove. The clamping mechanism comprises an overturning arm and a mechanical arm arranged on the overturning arm and corresponding to the end of the feeding groove. The overturning stopper adding and capping device is simple and compact in structure, easy to maintain, accurate and reliable in stopper adding and capping, high in production efficiency, high in universality of packaging materials, more clean in packaging process and capable of meeting the requirement for the new-edition GMP of pharmacy, and a relative friction movement component which may generate fine particles is not arranged above an opening of a packaging bottle in the stopper adding and capping process.