Abstract:Six steroid alkaloids, imperialine (Ⅰ), imperialine-3β-D-glucoside (Ⅱ), peimissine (Ⅲ), imperialine N-oxide (Ⅳ), cycloparnine (Ⅴ), and cycloposine (Ⅵ) were isolated from the bulbs of Fritillaria pallidiflora Schrenk. Their structures were determined from spectral data and chemical evidences. Imperialine N-oxide was first obtained from nature.