The influence of application parameters of unmanned aircraft on droplets deposition was researched. Temperature change rate was tested by thermal infrared imager to reflect the droplets deposit on rice canopy. The results showed that there was no difference with the droplets deposition and canopy temperature change rate as evaluation index. Thermal infrared imager could reflect the droplets deposit law exactly. The optimum application parameters of WPH642 unmanned aircraft were that flight altitude of 2m and flight velocity of 1.5 m/s. 