The invention discloses a method for depositing silicon carbide on the surface of a graphite part. The method comprises the following steps: (1) impurity removal of graphite surface: forming metal halides of impurities on the surface of the graphite part and removing through sublimation; and (2) CVD (chemical vapor deposition): conveying the treated graphite part into a CVD reaction furnace, and depositing a silicon carbide coating on the surface of the graphite part through a CVD reaction. In the invention, a pretreatment furnace is arranged in front of the CVD reaction furnace, the metal impurities contained in the graphite part react with a halogen gas to form metal chlorides which are removed through sublimation, the purification of the graphite part is facilitated, and the contained impurities are prevented from being mixed into follow-up systems. Moreover, through ultrasonic washing, the surface of the graphite part is further cleaned, and influence of the adherent particulate matters on the bonding strength of the silicon carbide coating is avoided.