Abstract: The urban wetland of Songbei District of Harbin,which is in the north shore of the Songhua River,was researched.Ten indicators were selected and factor analysis and cluster analysis adopted to analyze the change of ecological security of urban wetland before and after the Songhua River pollution.The results show that the ecological security rate in the east area before pollution is higher and the rate in middle area after pollution is lower;the anti-jamming ability in west area is worst;the drop degree in water factor was biggest,which shows that the water pollution directly affects ecological security of urban wetland.Finally,reasonable countermeasures of ecological security were put forward.