The invention belongs to the technical field of anchoring equipment and relates to an outer anchoring device for a nonmetallic anti-floating anchor. An anchor body consists of two parts, namely an inner anchoring section and an outer anchoring section; a positioner is arranged on the outer anchoring section and is separately connected with the anchor body and a steel casing; the steel casing is arranged is arranged at the outer side of the outer anchoring section; the steel casing, the outer anchoring section of the anchor body and the positioner are tightly bonded by adopting cement mortar; angle irons are welded on the outer wall at the bottom of the steel casing; the steel casing and the angle irons are fixed on a rock and earth mass by adopting a welding mode; a cushion is laid on the rock and earth mass and is separately connected with the inner anchoring section and the outer anchoring section; a waterproof steel plate is welded on the outer side wall of the steel casing; and the steel casing, the waterproof steel plate and the outer anchoring section of the anchor body form an integral structure which is cast in a reinforced steel base plate. The outer anchoring device has the advantages of simple structure, convenience in operation, low cost, convenience for mounting and construction, long service life, great anchoring force and good anchoring effect.