In this study， ACE inhibitory peptides were isolated and purified by ultrafiltration and strong anion exchange chromatography， and their peptide sequences were identified by LC-MS/MS. Fourier transform infrared spectroscopy， enzyme reaction inhibitor kinetics， MTT assay and molecular docking technology were used to analyze the secondary structure characteristics， in vitro activity and binding mechanism with ACE. The results showed that the activity of < 3 ku ultrafiltration fraction was better (IC50 value: 0.380 mg/mL)， and the activity of F-a fraction was the best (IC50 value: 0.159 mg/mL) after ion exchange chromatography. Four peptide sequences were identified by LC-MS/MS， and bioinformatics analysis further confirmed that the peptide PGDVF was a potential ACE inhibitory peptide with an IC50 value of (0.56 ± 0.1) mmol/L. the secondary structure analysis showed that PGDVF was composed of α-helix， β-sheet， β-turn and random coil， and its inhibition model may be mixed. The peptide concentration less than 1 mg/mL was basically non-toxic to HepG-2 cells. Molecular docking showed that PGDVF could be closely combined with ACE enzyme through hydrogen bond and hydrophobic force， thus effectively inhibiting ACE activity. In summary， this study can provide reference for the development and utilization of Prinsepia utilis decompression peptide.