From the cultured cells of Panax notoginseng, a kind of ginseng saponin-ginsenoside Rg2, was separated and purified, and its structure was elucidated as 6-O-[alpha-L-rhamnose (l-->2)-beta-D-glucopyranosyl]3beta, 12beta, 20(S)-trihydroxydammar-24-ene [20(S)-ginsenoside Rg2]. Moreover, its bioactivity stimulates human umbilical cord vein endothelial cell proliferation; the growth of the cells treated with 20(S)-ginsenoside Rg2 was 14-fold higher than that of untreated ones, and the level of the cell's plasminogen activator (PA) was also twofold higher.