Momordica charantia L. is a herbaceous climbing plant in the genus Momordica of family Cucurbitaceae. It is to study the chemical constituents of Momordica charantia L. leaves and establish the method for determination of their total saponin content. Momordica charantia L. leaves are isolated and purified by silica gel and Sephadex LH-20 column chromatographies, and the resulting compounds are structurally elucidated by NMR spectroscopy. Total saponins in Momordica charantia L. leaf extract are quantitatively determined by spectrophotometry with Momordicin I as the standard substance. Five compounds are isolated from the 80% ethanol extract of Momordica charantia L. leaves, which are identified as Momordicin I (1), Momordicin IV (2), Aglycone of Momordicoside ?(3), Aglycone of Momordicoside L (4) and Karavilagenin D (5), respectively. Total saponins have a good linear relationship with the absorbance within a range of 0.005~0.025 μg, recovery is 100.27%, and RSD= 1.20% (n= 6). The isolated compounds are all triterpenoids. The present quantitative determination method is simple, fast and accurate, which can be used as the method for determination of triterpenoid content in Momordica charantia L. leaves.