The utility model relates to a novel spray nozzle of an electric arc spray gun, which comprises a contraction section, a throat part and an expansion section of a central airflow channel of which the nozzle body cross section is quincuncial; the central airflow channel of which the nozzle body cross section is quincuncial is in a five-pedal-shaped channel shape or a six-pedal-shaped channel shape; and two sets of atomization air holes symmetrically arranged are respectively arranged above and below a five-pedal-shaped channel and a six-pedal-shaped channel. An action of compression and flattening can be performed on electric arc spraying atomization jets, thereby, the distribution of the whole atomization airflow field is even, and the thickness distribution of a spraying coating is evener. The bonding force, the spraying efficiency and the deposition rate of an electric arc spraying coating are obviously improved.