A method for measurement of the phospholipase A1 activity by acid-base titration with deoiled phospholipid as substrate was adopted in this paper, according to the characteristic of lipase Lecitase® Ultra which had both high lipase and phospholipase activity. The effect of some key factors on the measurement of enzymatic activity was evaluated, and a rapid and reliable method for measuring the phospholipase A1 activity of Lecitase® Ultra was established.