Abstract: Low pressure plasma spraying technology has unique technical advantages in the preparation of material surface coating and has a wide application prospect in industries such as aerospace, metallurgy, manufacturing, and so on. In this paper, an ejector device is installed on the outside of the plasma spray gun for powder injection. Aiming at improving the heating atomization effect of the powder with high melting point in the application of this technology, the influences of the structure of the ejector device, the position of powder injection, and the direction of powder injection on the heating atomization effect of powder particles are analyzed by means of numerical simulation. The main conclusions are as follows: installing an ejector device for powder injection is beneficial to improve the heating and atomization effect of powder particles. And Laval nozzle-type ejection device is beneficial to further improve the heating atomization effect of powder particles, but there is a certain risk of powder clogging. The expanded nozzle-type ejection device can effectively reduce the powder clogging risk, but the powder temperature and the overall heating atomization effect need to be further optimized.