Focus on the resources supply and demand, this paper selected representative indicators and established the index system.Using the generalized principal component analysis method, it evaluated comprehensive urban carrying capacity(UCC) of 16 cities of Yangtze River Delta in 2000-2009.The results showed that: the key impact factors of Yangtze River Delta Urban agglomerations UCC were transportation and environmental carrying capacity and the bottleneck lay in the development of scientific and technological capacity; Yangtze River Delta Urban agglomerations UCC showed upward trend and within the Urban agglomerations the UCC differences were narrowing; UCC value of Shanghai had been in widening, its main influencing factors were land and environmental carrying capacity and the short board of development is technology capacity. <<