The invention provides a preheating device for reducing the carbon content of zone melting monocrystals, wherein the preheating device includes a graphite preheating ring and a quartz separation piece; the graphite preheating ring has a cylindrical structure, a bowl-shaped groove sunken downwards is arranged on the upper top surface of the graphite preheating ring, and a through hole is formed inthe bottom of the bowl-shaped groove; the quartz separation piece is wrapped on an annular upper edge of the surface of the graphite preheating ring. The preheating device for reducing the carbon content of the zone melting monocrystals has good preheating effect and can effectively avoid occurrence of the carbon pollution condition of a polycrystalline masterbatch by the graphite preheating ring,avoids the carbon content in monocrystal silicon exceeding the standard, and effectively solve the problem of monocrystal branching caused because impurities are easily adsorbed on the surface of thegraphite preheating ring and enter a melting zone.