Angiotensin I-converting enzyme (ACE) inhibitory activities of thirty commercial Chinese style soy-paste were determined. All the aqueous sample extracts exhibited ACE inhibitory activities. Nine samples produced in Guangdong Province showed significantly higher ACE inhibitory activities than other samples (p < 0.0001) and the strongest activity was detected with an extraordinarily low IC₅₀ value of 0.012 mg/mL. Furthermore, these nine samples contained significantly lower peptide contents in line with the slighter proteolysis degrees and showed significantly lighter colors as evidenced by the higher L* (lightness) values than other samples (p < 0.0001). It was indicated that special processing techniques depending on production regions might, to a large extent, affect the ACE inhibitory activities of Chinese soypaste. The findings in this work would be useful in exploring ACE inhibitors derived from Chinese style soypaste and designing functional products with potential antihypertensive effects.