In this study, through optimizing the 5% abamectin EW formulation, stable formulation was determined, the optimum formula of 5% abamectin EW were as follows: Abamectin TC 5%, toluene 9%, cyclohexanone 6%, BY-125 7%, NP-10-P 1.34%, thickening agent (xanthan gum) 0.05%, anti freeze agent (ethylene glycol) 5%, defoaming agent 0.1%, distilled water or deionized water was made up of 100%. The product had good cold storage, heat storage and stability with time, was in conformity with the EW quality standard.