The invention discloses an external-scaffold-free external wall formwork system. The external-scaffold-free external wall formwork system comprises an external wall outer side formwork, an external wall inner side formwork and K plates; the external wall outer side formwork comprises an external wall outer side large formwork, back ribs, base plates and nuts which are mutually connected to form awhole structure; the external wall outer side large formwork is a whole large formwork, the back ribs are transversely fixed to the outer surface of the external wall outer side large formwork at equal intervals, the base plates are fixed to the back ribs correspondingly at equal intervals and provided with bolt holes, the nuts are fixed to the base plates, and screw holes of the nuts mutually correspond to the bolt holes in the base plates in positions; and in a fabricated mode, the upper part and the bottom of the external wall outer side large formwork are connected with the K plates correspondingly, and the external wall outer side formwork and the external wall inner side formwork are fixed together through split bolts. According to the external-scaffold-free external wall formwork system, the external wall outer side formwork can be mounted, demounted and reinforced without utilizing an external scaffold.