Abstract: Objective: To investigate the differential metabolic changes between two fermented milk beverages, Lactobacillus helveticus H11 and Lactobacillus paracasei Lc-01, during storage. Methods: The differences between volatile flavour substances, metabolites and ACE inhibition activity in the fermented milk beverages were analyzed using gas chromatography-mass spectrometry (SPME-GC-MS) coupled with high performance liquid chromatography (HPLC) and ultra-performance liquid chromatography tandem with quadrupole time-of-flight mass/mass spectrometry (UPLC/Q-TOF MS) techniques at 4 ℃, 28 d of storage. Results: After 28 d storage at 4 ℃, the in vitro ACE inhibitory activity of L. helveticus H11 fermented milk beverage was more than 60% higher than that of L. paracasei Lc-01, and the ACE inhibitory peptides VPP and IPP were also significantly higher than that of L. paracasei Lc-01(P<0.05). SPME-GC-MS was used to find that L. helveticus H11 fermented milk beverage was rich in aroma components, with relatively high contents of the characteristic flavour substances 2-heptanone and 2-nonanone, 43.84% and 12.39%, respectively. The results based on UPLC/Q-TOF MS showed that the main metabolic differentials of both fermented milk beverages during storage were peptides, amino acids and organic acids. Conclusion: L. helveticus H11 has great potential for the preparation of fermented milk beverages.