Abstract: Provided is a use of methylated locus in Sonic Hedgehog subgroup medulloblastoma, which relates to the technical field of tumor classification and detection. Specifically, the present disclosure provides a use of a reagent for detecting a methylation level of at least one genetic locus selected from ROBO4, OTX2OS1, AHRR, DKK4, or PART1 in a biological sample in the preparation of a diagnostic reagent or a diagnostic kit for Sonic Hedgehog subgroup medulloblastoma. Based on analysis and comparison of data from a large number of Sonic Hedgehog subgroup medulloblastoma samples and other medulloblastoma subgroups samples the methylation level of a genetic locus in the above genes can be used as a referenced indicator for the diagnosis of Sonic Hedgehog subgroup medulloblastoma. Therefore, only a few methylated loci are targeted and detected, and MB SHE can be classified and identified, thereby reducing diagnostic difficulty and cost of Sonic Hedgehog subgroup medulloblastoma.