Abstract: A process was set up to recover the water-soluble potentiator in the discarded supernatant from technical powder production of Bacillus thuringiensis MP-342 strain. This process consist s of vacuum evaporation and spray-drying. The maximum solid content in concent rated supernatant could reach to 45 %. The proper spray-drying condition was 300 ℃ at inlet , and 80 ℃ at outlet . The vacuum evaporation and spray-drying process showed no significant effect s on the activity of potentiator . The potentiator powder composed of 10. 58 % carbohydrate , 5. 82 % total nit rogen , 1.15 % fatty acids and plenty of amino acids and inorganic salts.