The invention provides an indole tetrahydrofuran oxide compound or a crystal form thereof, wherein the indole tetrahydrofuran oxide compound is as shown in a formula (I). R1 is selected from benzene rings, naphthalene rings and thiophene rings or cinnamyl, R2 is selected from H, F, Cl, Br and I or C1-3 alkoxy, R3 is selected from H and benzyl or C1-C3 alkyl, and R4 is H, F, Cl, Br, I and C1-3 alkoxy or C1-C3 alkyl. The invention further provides a method for preparing the compound. The compound is simple and convenient in preparation method, moderate in reaction and high in yield and has anti-tumor activity and a wide market application prospect.