Abstract: Ag/TiO₂ was modified by stearic acid to change its surface from hydrophilic to hydrophobic.Chlorfenapyr pesticide，modified Ag/TiO₂ and corresponding additives were mixed to fabricate a nano-pesticide formulation. The particles had uniform size, and the mean diameter was about 100 nm. The photodegradation experiment of chlorfenapyr nano-pesticide formulation proved that the preparation was stable in darkness, while the decomposition rate was 15.8％ with in lighted room after l5 days, and 69.0％ with irradiation under sunlight after 3 days.With irradialtion by UV-light for 22.5 h, the decomposition rate of nano-formulation was more than 9.2 times that of normal formulation. The indoor and field virulence experiments of chlorfenapyr nano-pesticide formulation indicated that nano-formulation had stronger virulence than normal formulation.The LC₅₀ was 8.95 mg•L^-1, more than 1.77 times that of EC virulence. Under the condition of half pesticide dosage in the comparative experiment of pesticide protection, the effect of preventing from cabbage Spodoptera litura F. was better than chlorfenapyr EC.
After using pesticide 1 day and 3 days，corrected protection effect of pesticide was higher by 4.89％ and 3.05％ respectively.The remnant pesticide experiments of soil and plants indicated that the decomposition of nano-formulation in cabbage and soil was quicker, and the t_1/2 was 3.91 and 1.27 days respectively. While the t_1/2 of chlorfenapyr SC was 8.64 and 3.27 days respectively.