Along with the accelerated process of urbanization,urban ecosystems are subjected to certain pressure,we employed principal component analysis method in the urban ecosystem research.We collected the relevant data from 2000 to 2008 in Yanzhou from the social,economic and natural departments.,Principal components(factors) were chosen from selected 32 factors affecting the urban ecosystem changes,the main factor was quantitative analyzed,.The results showed that the first three principal components contribute 88.158%,including most information of the original data.They can represent original indicators for analysis.The main factor affecting the Yangzhou urban ecosystem is divided into two categories:social factors and environmental factors.