Objective To study the bioactive constituents of the immature fruits of Citrus aurantium. Methods Silica gel and Sephadex LH-20 were used to isolate the constituents of this plant. The spectroscopic methods were applied for their structural elucidation. Results Four compounds were isolated from the ethanol extract of the immature fruits of C. aurantium. These compounds were elucidated as 3, 5-dihydroxyphenyl 1-O-(6′-O-trans-feruloyl)-?-D-glucopyranoside (Ⅰ), hesperetin (Ⅱ), 4′, 5, 7, 8-tetra- methoxyflavone (Ⅲ), and limonin (Ⅳ). Conclusion Compound Ⅰ is a new phenolic glycoside.