The invention discloses a fully-closed argon protection device. The fully-closed argon protection device comprises a steel ladle and a funneled brick; an argon protection ring is fixed to the lower portion of the steel ladle and comprises an upper ring piece and a lower ring piece which are fixed together with screws; a refractory material cylinder is connected to the bottom of the lower ring piece in a sleeving mode, and the funneled brick is sleeved with the bottom of the refractory material cylinder; a plurality of vertical argon jetting holes are formed in the lower ring piece annularly, and argon pipes are connected with the argon jetting holes; an annular fire-retardant elastic piece is arranged on the top of the refractory material cylinder; two elastic metal rings are arranged in the annular fire-retardant elastic piece concentrically; a plurality of conical sleeves are connected between the two elastic metal rings; and thread sleeves in one-to-one correspondence with the conical sleeves are arranged at the bottom of the annular fire-retardant elastic piece and internally connected with adjusting bolts in a threaded mode, and the adjusting bolts and the conical sleeves makeselective contact. The defects in the prior art can be improved, and the universality of the protection device is improved.