In order to analyze the pollution characteristics of water environment in Xi'an moat, the paper measured the indexes including DO, CODCr, TN, NH3—N and TP from 10 sampling points and analyzed its pollution causes.The results show that DO, CODCr, TN, NH3—N and TP presents a gradual increase trend with the flow along south-west section of Xi'an moat from sampling points A1 to A5, which indicates that the south-west section may be mainly affected by endogenous pollutants;While these parameters have no obvious variation trend along the east-north section from sampling points B1 to B5,but in the sampling point B3, the indicators such as CODCr、TN、NH3—N and TP reached the maximum value in 10 sampling points, which shows that the east-north section may be polluted not only endogenous pollutants, but mainly polluted by exogenous pollutants.The paper applied integrated evaluation method of urban river environment to establish the comprehensive evaluation index system and evaluation model of Xi'an moat.The results show that overall water environmental quality level is poor,that of the southern section is relatively good, that of the western part and the eastern section is the second, and that of the northern section is the worst.