Abstract: The colorimetric method was used for quantification of triterpene saponin with vanillin reagents as colorant, and the accuracy, reproducibility and stability were tested. The contents of total saponin in 4 legumes (Astragalus sinicus, Onobrychis viciaefolia, Lotus corniculatus and Coronilla varia) were determined with the above method. The results showed that the method was simple with high accuracy and reproducibility, and very stable within 25 min. The variation of total saponin contents of 4 legumes was not same. A. sinicus and O. viciaefolia in early flowering stage were proper for feeding livestock or hay making because of the low saponin content, high yield and excellent quality, meanwhile, these two legumes were better be used as material for saponin extraction in flowering stage because of the high saponon content and the highest yield. C. varia, remained lower saponin content and no ruminant distension of abdomen, was a highquality legume forage. The content of total saponin in leaf were much higher than in stem.