Abstract: A survey was conducted on Black-necked Cranes (Grus nigricollis) and their breeding success from April-September, 2013 at Ruoergai National Nature Reserve. There were 893 Black-necked Cranes in September, including 174 breeding pairs (348 birds), 275 chicks, and 270 non-breeding individuals. The cranes mainly were recorded at Huahu, Cuolajian, Haqiu, and Cuoqiu Lakes and the surrounding marshes, as well as riverine marshes at Lalianqiao, Heiqinqiao, and Nanenqiekai valleys. All of them, 70% were breeding pairs, 30% were non-breeding individual, with a largest flock of 106 birds was recorded. Of all breeding pairs, 90.2% had their eggs laid and hatched, mostly in June with 151 chicks (54.5%). Number of chicks accounted for 30.8% of the total number of Black-necked Cranes in September. Effective measures should be taken to protect lakes and other wetlands that are used by Black-necked Cranes for breeding at Ruoergai.