On the basis of the theory of eco-economics and by the applying analy tic hierarchy process(AHP),an evaluation index system and an evaluation model for compreneasive ecological benefits of the returning farmland to afforestation in the upper reaches of the Yellow River are proposed.A case study was carried out in Datong County,Qinghai Province,for comprehensive ecological benefits of the returning farmland to af forestation in the vegetationtypes of nature spruce forests,reuse farmland for woodland,natural wasteland and natural shrub in comparisonwith the agro-ecosystems.Results show that ecological benefit indexes of all the vegetation types,such as naturalspruce forests,reuse farmland for woodland,natural wasteland and natural shrub,are higher than that of theagro-ecosystem.The comprehensive ecological benefit indexes are in an order of natural spruce forests > reuse farmlandfor woodland > natural shrub > farmland > natural wasteland.The study results can be referred for the ecologicalregeneration project of the returning farmland to afforestation in the upper reaches of the Yellow River.