[ Objective] The paper was to prepare bifenthrin nanoemulsions, and to characterize its property. [ Method ] Oil in water type of bifenthrin nanoemul- sions was prepared using emulsion phase transition method at constant temperature of 25℃. The formation mechanism of nanoemulsions was investigated, and the property of bffenthrin nanoemulsions was characterized by dynamic light scattering（DIS）, transmission electron microscopy （TEM）, contact angle meter, interfa- cial tension meter and high performance liquid chromatogTaphy （HPLC）. [ Result ] Phase transition occurred during the formation progress of bifenthrin nanoemul- sions ; the particles of nancomulsions system was spherical, and the particle size was mainly distributed in the range of 25 -30 ran; the contact angle on paraffin was less than 90° with good wetting effect; the surface tension was less than 40 mN/m, and the emulsification effect was also good, so the utilization rate of bifenthrin nancomulsions was improved. HPLC results showed that bffenthrin was not easy to decompose or precipitate with good stability. [ Conclusion] The result provided basis for the preparation of new types of insecticides.
