The invention provides a beauveria bassiana preparation for controlling peach fruit borers and a preparation method thereof. The preparation method comprises the following steps of: inoculating a strain of beauveria bassiana with the collection number of CGMCC No. 4526 into a test tube loaded with a PDA (potato dextrose agar) slant culture medium containing a healthy peach fruit borer corpse leachate for culture, further performing second-stage strain culture and third-stage solid amplification culture, and finally preparing a bacterial powder preparation. The bacterial powder preparation provided by the invention has a better effect on controlling the peach fruit borers, the control effect can be up to 90.5%, and the fruit-boring rate of an orchard in the same year can be reduced by 83.8% -93.6%. The bacterial powder preparation provided by the invention is particularly suitable for controlling the peach fruit borers in dry and low-temperature regions in the north.