The invention discloses a polished rod sealing device for a production well. The polished rod sealing device comprises a packing, a packing cover, a nut and a gland; the packing sleeves a polished rod; the packing cover sleeves the packing; the nut fixedly connected with the upper portion of the packing cover sleeves the polished rod; the gland abutted to both the nut and the packing sleeves the polished rod. An oil storage cavity forms among the nut, the gland and the packing cover. The nut is further provided with an oil incoming hole communicated with the oil storage cavity. A guide passage forms between the gland and the polished rod. The nut is provided with an oil hole whereby the oil storage cavity is communicated with the guide passage. The polished rod sealing device allows the polished rod and the packing to be continuously lubricated without machine halt, dry friction between the polished rod and the packing is avoided, the packing is kept be in a good operating mode constantly, productivity of an oil well is improved, service life of the packing is prolonged, and waste of the packing is avoided.