The invention belongs to the field of health-care foods and relates to an Inonotus obliquus oral liquid preparation method, comprising the steps of A, treating culture mother liquid; B, treating with a shaker; C, sterilizing the liquid medium in a large tank; D, inoculating; F, collecting the liquid, to be specific, hermetically packing the liquid medium containing Inonotus obliquus mycelia in the large tank to obtain the Inonotus obliquus oral liquid. The method of the invention is convenient and simple to perform. The Inonotus obliquus oral liquid has the outstanding effect, namely excellent hypoglycemic and anti-hyperglycemia effect; the process of the finished oral liquid from material to processing is completely green. After the Inonotus obliquus oral liquid is continuously taken for 2 months, each assay index of diabetics gains significantly improvement; after the Inonotus obliquus oral liquid is continuously taken for 6 months and longer, a patient with medium- and light-degree diabetics may recover and has no need to take medicine. The Inonotus obliquus oral liquid may also improve body immunity, fight cancers, relieve the unique pain in cancer sufferers, repair injured pancreatic tissues, prevent and treat diabetic multiple system organ complications, subside inflammations, and prevent cold.