The invention discloses a sealing device with a magnet ring. A through hole for allowing a guide wire to penetrate into a soil pressure box is formed in the soil pressure box; a sealing device for sealing a gap between the guide wire and the through hole is arranged between the guide wire and the soil pressure box; the sealing device comprises a sealing sleeve which tightly covers on the guide wire and an adsorption cover which covers the through hole in a sealing mode; the inner part of the adsorption cover is hollow; openings are formed in the top end and the bottom end of the adsorption cover; the area of the bottom-end opening of the adsorption cover is greater than that of the top-end opening of the adsorption cover; the adsorption cover is a soft cover; the top end of the sealing sleeve is fixedly arranged on the guide wire in a gas-tight mode; the bottom end of the sealing sleeve is in sealing connection with the top-end opening of the adsorption cover; the bottom end of the adsorption cover is fixedly arranged on the outer surface of the soil pressure box in the gas-tight mode through an adsorbing device; and the inner cavity of the sealing sleeve communicates with the inner cavity of the adsorption cover to form a channel for allowing the guide wire to penetrate through.