The present invention relates to a purification method for dodecanedioic acid produced through biological fermentation. The purification method comprises: (1) heating a dodecanedioic acid fermentation termination liquid, carrying out demulsification, and filtering through a ceramic membrane and an ultra-filtration membrane to remove solid particles, macromolecular proteins and pigments so as to obtain an ultra-filtration liquid; (2) mixing the ultra-filtration liquid obtained in the step (1) and isoamyl alcohol to obtain a mixed liquid, and heating to a temperature of 40-90 DEG C; (3) carrying out thermal insulation, adding concentrated sulfuric acid to the ultra-filtration liquid on the bottom portion of the mixed liquid, adjusting the pH value to 2-6, carrying out stirring mixing, and standing; and (4) taking the upper layer extraction phase, carrying out cooling crystallization, washing the filtered crystal, and drying to obtain the dodecanedioic acid crystal. According to the present invention, the dodecanedioic acid product is refined through the extracton method, the total acid number of the purified product is more than 99%, and the total nitrogen content is less than 30 mg/kg.