Abstract: In order to clarify the mechanism of pinolene and improve the control effect of pesticides in the field, the film-forming properties of pinolene on leaves were investigated. Pinolene was added to 3% thiacridacin microcapsule suspension and 2% emamectin benzoate microemulsion, respectively. And the mixtures were sprayed on leaf of Photinia × fraseri Dress. and Carya cathayensis Sarg. Influences of pinolene on the leaf surface morphology and photosynthetic characteristics were detected by electron microscopy and photosynthesis system. Rainfastness and anti-photolysis capacity of pinolene were studied by artificial stimulation of rainfall and xenon lamp. The results showed that there was a clear coating of oil on the surface of the drug particles in the pinolene-treated group. In the rainfastness test, the residue of thiacloprid in the pinolene-treated group on the leaves was significantly higher than that in the control group during different periods. Using pinolene with emamectin benzoate can significantly reduce the photolysis rate of emamectin benzoate. The photosynthetic rate decreased by 5.16% due to film-forming of pinolene on the leaves, which was not significantly different from the control group. The addition of pinolene in pesticides can immobilize the active ingredients on the leaves of the plants, effectively improve the rainfastness, reduce the photolysis rate of the pesticides and extend the pesticide holding period. While it has little effect on the photosynthesis of the plants.