An inner bore plasma spraying method comprises the following steps: first, adjusting the spraying position between a plasma cylindrical spray gun and a workpiece inner bore; then sending powder by a radial upward powder sending manner from the lower part of the pray gun; finally, according to the different spraying powder adjusting the flow amount of a powder sending gas to enable the powder to be fully heated and melted in the flame and upward shift a right angle. The inner bore plasma spraying method uses the radial upward powder sending manner from the lower part of the pray gun for powder sending, and the flow amount of the powder sending gas can be adjusted according to the different spraying powder, so that the powder can be fully heated and melted in the flame and upward shifts a right angle, the formation of spraying dead angles on the upper edge of the inner bore can be avoided, the coating performance of a coating on the upper edge of the inner bore can be improved, the hollow and empty spray problems of the coating can be avoided, and the inner bore plasma spraying method has the advantages of simple operation and strong practicability, and is suitable for the atmospheric pressure plasma or low pressure (vacuum) plasma spraying.