The α-Mangostin and -Mangostin were mainly isolated from Garcinia Mangostana L. as representative Xanthone's natural products of plant origin, revealed high activity of antitumor, antioxidation and other diverse pharmacological activities. A series of α, γ-Mangostin derivatives LT-1~17 has been synthesized, and confirmed by 1H NMR, 13C NMR, MS(supplement file). Compounds LT-2~17, as novel Xanthone, have been reported for the first time. Their antitumor activities have been investigated by MTT method in cell lines: A549, K562, CNE, KB-3-1, MCF-7 and HepG2. A number of compounds showed potent anti-tumor activity, in some cases even higher (more effective) than Mangostins. Compound 3 with an IC50 value of 1.73 µM in the A549 cell line, which was two-fold, acted more active than ADM (adriamycin) and α, γ-Mangostin, and had the most potent anti-tumor activity (IC50=2.15 µM) for the MCF-7 cell line in all synthetic derivatives. α, γ-Mangostin and ADM showed potent anti-tumor activity (IC50=2.82 µM) for HepG2 cell line, and less potent anti-tumor activity in other cell lines compared with the compound LT-12. It was obtained by esterification of the C-3, C-7 phenolic-OH of the α-Mangostin with acetyl group resulted the potent anti-tumor acvitity, which indicated that the phenolic-OH of the Mangostins had a great impaction on the anti-tumor activity of Mangostins.