In order to realize the high value utilization of the skin of navodon septentrionalis， the optimal enzyme hydrolyzation technology for preparation of angiotensin converting enzyme (ACE) inhibitor peptide from collagen was studied. The ACE inhibitory peptides was separated， purified and analyzed by ultrafiltration， gel chromatography， high performance liquid chromatography (HPLC) and UPLC-MS. In addition， the effect of the pH， temperature and simulating gastrointestinal digestion on the stability of the ACE inhibitory peptides were assessed. The result revealed that the optimal parameters for producing protein hydrolysates with the highest ACE inhibitory activity were as follows: hydrolysis time 4 h at pH 8， Protease N “Amano” 2Genzyme dosage 1 200 U/g as well as trypsin enzyme dosage 2 400 U/g， hydrolysis temperature 40 ℃， and the enzyme-to-substrate ratio 4%. Under these conditions， the ACE inhibitory rate of enzymatic hydrolysates could reach 74.3%. After ultrafiltration and gel filtration， three high activity component (a1， a2， a3) were obtained， the stability study showed that the three high activity component(a1， a2， a3) maintained high activity under the thermal， acidic， mildly alkaline condition and demonstrated good stability in gastrointestinal digestion environment. Among them， a1 showed the best ACE inhibitory activity and stability. HPLC and UPLC-MS analysis showed that the purity of a1 was high， which amino acid sequence might be Gly-Val-Ala or Ala-Val-Gly. The above results provide a theoretical basis for the intensive processing of navodon septentrionalis skin and the development of new ACE inhibitors.