Three new oleanane saponins (1–3), together with four known ones (4–7), were isolated from the aerial parts of Polyscias guilfoylei. Their structures were elucidated by 1D and 2D NMR experiments, including 1D TOCSY, DQF-COSY, ROESY, HSQC, and HMBC spectroscopy, as well as ESIMS analysis. The antiproliferative activity of all compounds was evaluated using three murine and human cancer cell lines; J774.A1, HEK-293, and WEHI-164. All the compounds were inactive except for 3β- O-[β-D-glucopyranosyl-(1→2)-α-L-arabinopyranosyl]-echinocystic acid 28-[ O-β-D-glucopyranosyl-(1→6) O-β-D-glucopyranosyl] ester (3), which was active against all the cell lines.