Abstract: For temperature and velocity of particles in plasma spraying may influence the final quality of coatings directly,through orthogonal experiment of plasma sprayed Al₂O₃-13%（w）TiO₂ coatings,the effects of voltage,current,powder feeding speed and primary air pressure on particle states including temperature and velocity were investigated.Additionally,characterization models of particle states in plasma flame were established based on the monitoring results.These models can supply a way for forecasting particle states and thus controlling coating characteristics.