Abstract: This study delt with quantitative analysis for diets taken in by a group of Rhinopithecus bieti in wild,and tested its principal types of diets among the residues from its excrements.Through the determination of digestive ability from an individual of R.bieti in captivity,an equantion about quantity of diets taken in by wild R.bieti groups was established.The results have indicated that,in this group of R.bieti,Per 0.49 kg residuary compounds excreted must correspond to 12.5 kg of grass belonging to Monocotydoneae,21.7 kg of lichens,but only 1.1 kg of leaves of Abies sp.etc.taken in (all are dry weights).These data had been analysed with statistics,and test of null hypothesis indicated that Abies sp.are less important diets than the two above.