In this work, four new cyclodepsipeptides, fusarihexins C-E (1-3) and enniatin Q (4), four new cyclopentane derivatives, fusarilins A-D (5-8), together with eight known compounds (9-16), were isolated from cultures of the endophytic fungus Fusarium sp. The structures of the isolated compounds were elucidated by analysis of HRMS and NMR spectroscopic data. The absolute configurations were determined using Marfey's method, a modified Mosher's method, single-crystal X-ray diffraction analysis, and ECD analysis. The antitumor activities of the isolated compounds in vitro were evaluated. Cyclodepsipeptides displayed cytotoxicities against the Huh-7, MRMT-1, and HepG-2 cell lines. Compounds 4, 9, 10, and 12 with IC50 values of 1.0-9.1 μM exhibited the most potent cytotoxicities against the three cell lines as compared to the positive control-5-fluorouracil. Compounds 1-3 and 11 exhibited moderate cytotoxic activities (IC50 values of 10.7-20.1 μM).