The invention relates to application of scutelloside in pharmacy. The scutelloside promotes a T cell to be transformed toward Treg with immunological suppression effect by up-regulating the expression of Foxp3; at the same time, the scutelloside inhibits Th17 with pro-inflammatory effect and inhibits vasculitis mediated by the Th17. A main mechanism of inhibting the Th17 of the scutelloside is to inhibit the amplification of the Th17 mediated by IL-6. At the same time, a further experiment proves that the scutelloside taken as a novel immunomodulator plays good therapeutic effect on treating lupus erythenlatosus nephritis and rheumatoid arthritis.