Numerical simulation of in-flight particles in thermal plasma jet is one of the most important research fields. It has been used to analyze the influence of spray parameters on jet characteristics and to improve the quality of coating during plasma spraying. In this study, in-flight behavior of a group of lanthanum zirconate (La₂Zr₂O₇) particles with different diameters (10-60 μm) in gas tunnel type plasma jet is investigated by numerical modeling. The influence of torch power on the plasma jet is investigated and its interaction with different sizes of La₂Zr₂O₇ particles is studied under optimized spraying conditions. The resultant coating properties are also investigated and correlated with simulation results. The simulation results showed that the plasma jet temperature and velocity increased while increasing the torch power. Consequently, the in-flight particle temperature and velocity profile also increased with respect to the torch power.