The invention relates to a specific detection kit for isaria farinosa and a detection method thereof. The kit comprises a Tar-1F/Tar-1R primer pair, wherein sequences of the Tar-1F/Tar-1R primer pairare shown as SEQ ID NO. 41 and SEQ ID NO. 42; the primer can be used for specifically recognizing the isaria farinosa; the invention further discloses the method for detecting isaria farinosa pollution in a soil sample; soil sample detection is realized by washing a soil sample through a washing solution, treating by utilizing a lysis solution, lysozyme and proteinase K and purifying the soil sample and detecting. According to the method provided by the invention, humic acid in soil is removed and a condition that a detection result is influenced, caused by covalent binding between humic acidchelated Mg<2+> and an HiFi enzyme or DNA (Deoxyribonucleic Acid), is prevented; the accuracy is good and the sensitivity is high; the invention further discloses a method for detecting isaria farinosa pollution in polypides and has important meanings on isaria farinosa detection in an artificial cultivation process of caterpillar fungus.