Abstract: The heat transfer between powder particles and the argon plasma transferred arc (PTA) fluid was theoretically analyzed and measured in this article based on heat conduction theories.It was found that the elevating velocity of particle's temperature in PTA plasma fluid mostly depend upon the plasma fluid's thermodynamics,particle's thermodynamics,mass density and particle's sizes.In the central plasma fluid with 100~200 A surfacing currents,not only the Fe base particles with a relatively lower melting point but also the boron carbide(B₄C) particles with a relatively much higher melting point might be fully fused within milliseconds.However,the temperature elevation of Fe base particles is about one time faster than that's of boron carbide (B₄C) particles