In comparison with typical external feedstock mode, powders internal injecting method can effectively enhance plasma sprayed ceramic coatings performance and improve powder deposition efficiency. In this feedstock mode, spray powders were injected into the hotter regions of a plasma jet, which had enough heat capacity to melt most of the particles instantly. Currently, several plasma spray guns in internal feedstock mode, such as Axial III and SG100, have been developed and commercialized. In this paper, characteristics of plasma spray guns in internal and external feedstock methods were summarized. And the research status of the plasma spray torch in internal feedstock mode was particularly presented. Finally, the development trend of different feedstock modes adopted by plasma spray gun was discussed.