Abstract: The purpose of these studies was to improve the properties of rotenone formulation in stability, suspension and bioactivity. Aqueous nanosuspension of rotenone was prepared. Several characterizations of aqueous nanosuspension were detected by HPLC and environmental scanning electron microscope. The results showed that the average diameter of suspended particles was 127.1 nm±31.8 nm, the incorporation efficiency of nanoparticles to rotenone was 81.7%, and the suspension rate was up to 99.23%±0.49%. The rotenone degradation by UV light exposure was decreased by 68.9% after the formation of aqueous nanosuspension of rotenone. It was also found that the aqueous nanosuspension of rotenone bioactivity against Bursaphelenchus xylophilus was 7.5 times higher than those of rotenone for 24 h treatment.