Abstract: Understanding the distribution and population size information is essential to conservation and management of endangered species. In June and July 2009, we carried out a survey on Black-necked Cranes (Grus nigricollis)at Ruoergai (Zoige) Wetland (including Ruoergai, Hongyuan, Aba, Maqu, and Luqu counties). We visited 95 areas with Black-necked Cranes previously recorded or potentially to be found, while many possible areas were not visited either due to time constraints or not accessible. We sighted 728 Black-necked Cranes. Ruoergai County had the highest count of cranes, followed by Maqu County, Luqu County and Hongyuan County. No cranes were recorded at Aba County. Most Black-necked Cranes were concentrated at Huahu-Cuorewajian-Haqiucuogan Wetland in Ruoergai County, Manrima-Cairima Wetland in Maqu County, and Riganze Wetland in Hongyuan County. We estimated a total of 2,635 Black-necked Cranes breeding and summering at Ruoergai by extrapolating the density of cranes in the visited areas to the whole Ruoergai Wetland.