Abstract: In the process of pesticide application, pesticide formulation needs to be diluted according to the different application methods and the liquid properties are influenced by the dilution ratio. In this work, lufenuron EC was selected as the object. The effects of dilution ratio on the mechanism of emulsion properties and the wetting ability were studied. The results demonstrated that with the increase of the dilution ratio, the particle size of the emulsion decreased gradually and the particle size distribution became better. Besides, the particle size of the emulsion decreased and the Brownian motion of particle enhanced, so the sedimentation rate fell down and the centrifugal stability improved gradually. However, because the concentration of adjuvant decreases, the surface tension of emulsion increased and the contact angle of droplets on the hydrophobic paraffin wax surface increased gradually and the wetting properties became worse. This research has provided basis for pesticide normative application based on different application methods, which guides the improvement of the utilizing efficiency of pesticide.