The invention discloses an automatic welding method with a narrow-gap pulse consumable electrode and gas protection of petroleum kellies and includes the steps that firstly, round auxiliary blocks are respectively arranged on end surfaces of two kellies to be welded to cause a groove of a whole ring narrow-gap welded joint of the kelly to become a regular ring narrow-gap groove from the irregularity; then the automatic welding method with gas protection and the pulse consumable electrode is used for welding, and after the welding is finished, the auxiliary blocks and the raised part of the welded joint are processed to keep the original shapes of the kellies. As the round auxiliary blocks are respectively arranged on end surfaces of two kellies to be welded, the groove of the whole ring narrow-gap welded joint of the kelly is caused to become a regular ring narrow-gap groove from the irregularity, the method ensures the gas protective effect in the welding from a bottom drawing arc to the surface and the stability of the electric arc burning and the molten pool state of the electric arc and improves the quality of the welded joints.