A new racemic mixture of a 4-hydroxytetralone derivative, altaicusin A (1), was isolated from the whole plant of Eremurus altaicus (Pall.) Stev., together with three anthraquinones (compounds 2-4) and two naphthalene derivatives (5-6). The racemic altaicusin A (1) was further purified by chiral HPLC to yield a pair of enantiomers, (+)-(4S)-altaicusin A (1a) and (-)-(4R)-altaicusin A (1b). Their structures were established on the basis of spectroscopic analysis, including IR, HR-TOF-MS, and NMR. The absolute configurations of compounds 1a and 1b were elucidated by quantum chemical ECD calculations. Compounds 3 and 6 exhibited inhibitory activity against protein tyrosine phosphatase 1B (PTP1B).