Objective To investigate the chemical constituents from the fruits of Phyllanthus acidus, and their anti-hepatitis B virus (HBV) activities and pancreatic lipase inhibitory activities. Methods The chemical constituents isolated from the fruits of Phyllanthus by chromatographic separation techniques, including macroporous adsorption resin, MCI, Silica gel, Sephadex LH-20, and semi-preparative HPLC. The structures of the compounds were identified by HRESIMS, IR, 1D and 2D NMR, and ECD calculations. Additionally, the anti-HBV activities and the pancreatic lipase inhibitory activities of the obtained compounds were tested using the HepG2.2.15 cells and porcine pancreatic lipase, respectively. Results Thirteen compounds were isolated from the fruits of Phyllanthus acidus, including one novel norbisabolane sesquiterpenoid (1). The remaining compounds were identified as norbisabolane sesquiterpenoids(2-4), a cadinane sesquiterpene (5), flavonoids (6-8), a diterpene (9), an alkaloid (10), and lignan derivatives (11-13). The results of activity test showed that no obvious anti-HBV activity(at 30 μM) and pancreatic lipase inhibition activity(at 200 μM). Conclusion All the compounds were obtained from the fruits of Phyllanthus acidus for the first time, and compound 1 was identified as a new norbisabolane sesquiterpenoid. The anti-HBV activities and pancreatic lipase inhibitory activities of all compounds were tested, which provided a reference and scientific basis for the further development and utilization of this plant resource.