The invention discloses a nickel-based double-metal composite pipe all-position automatic welding method. The method includes the steps that (1), pipe ends of two composite pipes are machined into platform-shaped beveled edges; (2), the two composite pipes are in butt joint through internal clamps in the pipes; (3), coating layer backing welding and transition layer welding are performed in sequence through TIG welding or hot wire TIG welding; (4), base layer welding is performed through TIG or MIG welding. The same nickel-based alloy welding material is adopted for the coating layer welding, the transition layer welding and the base layer welding, and the Ni content of the nickel-based alloy welding material is higher than or equal to that of the coating layer. By means of the machined platform-shaped beveled edges, it is avoided that coating layer nickel-based metal and base layer metal dilute each other, and the corrosion performance of a nickel-based composite pipe circumferential weld is guaranteed; and the same nickel-based alloy welding material is adopted for all layers of welding, the requirements for coating layer metal corrosion and base layer toughness are met, and it is avoided that the nickel-based alloy base layer ring welding generates hot crack defects.