The invention relates to a drill stem protective cap with an embedded ring. The drill stem protective cap comprises a protective cap body. The protective cap body is in an annularly-conical shape adapted to the appearance of the end of a drill stem and comprises an expanded-opening end and a contracted-opening end; a placement opening for the end of the drill stem is formed in the expanded-opening end; the inner wall of the protective cap body is provided with an inner thread matched with a thread of the end of the drill stem; the contracted-opening end is a non-closed end; the rim of the contracted-opening end is bent inwards to form the embedded ring; and an embedded groove is formed between the embedded ring and the inner wall of the protective cap body. After the protective cap body is installed to the end of the drill stem, the end face of the drill stem is clamped into the embedded groove. The protective cap body is provided with oil replenishment holes close to the expanded-opening end. The contracted-opening end is provided with a circle of notches; and the notches penetrate through the embedded ring. Due to the fact that the two ends are each of an open structure, the weight of the protective cap is reduced; the drill stem protective cap is provided with the embedded ring, the end face of the drill stem is clamped into the embedded ring in the installation process, so that connection between the protective cap and the drill stem is reinforced, and the rim of the drill stem can be protected; and the drill stem protective cap is provided with the oil replenishment holes, and thus oil liquid can be replenished conveniently without unscrewing the protective cap.