The present application discloses an indole as represented by formula (I) used as a CRTH2 inhibitor, and a pharmaceutically acceptable salt or tautomer of the indole, and an application of same in treating a disease related to a CRTH2 receptor.本發明提供作為CRTH2抑制劑的式(I)所示的吲哚類化合物或其藥學上可接受的鹽或互變異構體,以及其在治療與CRTH2受體相關的疾病中的應用。