Abstract: The liquid whistle ultrasonic emulsifying equipment was used for making DDT emulsions. The favourable temperature of treatment was found to be at 40-48℃, and the time of treatment was 30 minutes. Stabilities of emulsions under influences of tem- perature, pH and electrolytes were studied. The sulphite liquor (from the Sulphite pulp process) as an emulsifying agent produced the most stable emulsion. This emulsifying agent was found to be less surface active, and more resistant to the change of pH and to electrolytes than Turkey red oil, but to produce stronger interfacial film. Therefore the strength of interfacial film and chemical nature of the emulsifying agents were considered to be important factors affecting the stability of emulsions.