Abstract: Cryoconite granules are dark-colored spherical aggregates of organic and inorganic material on glacier ice，and are commonly observed on glaciers over the world. Cryoconite granules are the main impurities on glacier，it can reduce the albedo of glacier surface markedly. 5 ice samples were taken from the Yushugou Glacier，Hami Prefecture，Xinjiang，China，in August 2011. By using the methods of paraffins section technology，16SrRNA phylogenetic analysis and mineral particles analysis，this paper studied the structure，formation process of cryoconite and discussed the main factor（organic part or inorganic part in cryoconite） of low albedo on glacier. The results showed as follows：（1） cryoconite granules distributed over the entire ice surface of the ablation area or cryoconite holes，and the size ranged from 0.22 to 2.9 mm （mean 1.0 mm）. The compositions of cryoconite granules are mineral particles，organic matter and microbes （cyanobacteria is the main microbe）. Cryoconite granules have four inner structures：Type 1，there are cryoconite granules that have no specific internal structure—mineral particles and organic matter distributes uniformly in the cryoconite. This type may be the primary form of the cryoconite. Type 2，some granules contain two or more sub granules. This type comes from the combination of small cryoconite granules. Type 3，some cryoconite granules have concentric layers of dense organic matter. Type 4，some granules have relatively large mineral particles in their center. Cryoconites have seasonal growth and an annual cycle of growth and dissociation. （2） 214 positive clones were randomly selected from the clone library and these positive clones were screened and grouped into 9 operational Taxonomic Units （OTUs） through ARDRA. 9 operational Taxonomic Units were divided into 3 phyla through sequences of gene，blast analysis and phylogenetic analysis：Oscillatoriales，Chroococcale and Unclassified. Oscillatoriales（95.8%） was the absolutely dominant group. （3） Mean mass concentration of mineral particles on the Yushugou Glacier was d<3.5 μm，volume median diameters of volume size distributions of mineral particles was 13 μm. Based on a comparison of the volume median diameters of volume size distributions of mineral particles between  Urumqi Glacier No.1 and Qingbingtan Glacier No.72，the volume median diameters of mineral particles on the Yushugou Glacier is higher. （4） the size of cryoconite ranged from 0.22 to 2.9 mm （mean 1.0 mm），so the mean volume of single cryoconite granule is 4.13 mm³. However，the mean size of single mineral particle is only 3.28 μm and the number of mineral particles in single cryoconite granule is small. After estimation，the proportion of organic matter is higher than that of mineral particles. The conclusion is that there are abundant organic matter and microbes in cryoconite，so the main factor of lower albedo is organic part，including organic matter and microbes. The previous researches mainly focus on the influence of mineral particles and black carbon on albedo of glacier ablation. Cryoconite granules as the crucial impurities on glacier can reduce the albedo of glacier surface markedly. However，the characteristics and formation process of cryoconite were rarely studied in China. It is a new field in the glacier area. Thus it is important to study the cryoconite on glacier.

Key words: the Yushugou Glacier, cryoconite, organic material, cyanobacteria, mineral particles, albedo