The invention discloses a preparation method of beauvericin. The method comprises the steps of 1a, preparation of a fusarium LF061 seed solution preparation:inoculating a slant culture or spore liquid of strain LF061 into a seed culture medium, and culturing for 48-72 hours with a rotating speed of 120-160rppm at 28-32 DEG C to obtain the seed solution; 1b, preparation of beauvericin from the fusarium LF061 seed solution through fermentation: inoculating the seed solution of which the inoculation amount is 5-15% in percentage by volume into a liquid fermentation culture medium, wherein the fermentation temperature is 28-32 DEG C, the rotating speed is 120-160rpm, the ventilation volume is 10-30L/min, and the fermentation time is 96-144 hours; separating and refining obtained fermentation liquid to prepare beauvericin. According to the method disclosed by the invention, the beauvericin is produced through liquid fermentation, and the prepared beauvericin is high in purity and recovery rate and adaptable in industrial production.