Abstract: This study investigates the spheroidization of boron carbide (B₄C) powder using radiofrequency inductively coupled plasma (RF-ICP) through experimental and simulation approaches. Under experimental conditions involving varying concentrations of helium (He) added to the plasma working gas, the effects of He doping on the surface morphology and particle size distribution of spheroidized B₄C powder are compared, with particular focus on the influence patterns on the spheroidization rate. Meanwhile, three-dimensional numerical simulations were coupled to analyze the interaction between plasma and powder particles, revealing the mechanism by which He addition influences the thermodynamic properties of the plasma and the plasma-particle heat transfer process. The results indicate that during the RF-ICP spheroidization of B₄C powder, the addition of He not only enhances the thermal conductivity of the plasma but also increases its enthalpy by raising the specific heat capacity. This enables particles to absorb more net heat during their residence time in the plasma. Consequently, both the spheroidization rate of B₄C powder and the energy utilization efficiency of the plasma are significantly improved. This study has important scientific significance and reference value for the plasma-based preparation of high-quality spherical B₄C powder.