Cobalt in 306 coal samples from Xinjiang was determined by inductively coupled plasma mass spectrometry (ICP-MS). The Co concentrations of coal in Xinjiang are obviously higher than Co concentrations both in China and abroad, and the cobalt content of the early-Jurassic coal is much higher than that of the middle-Jurassic coal in Xinjiang. Statistics show that Co is existent predominantly in the organic binding state in coals of Kubai and Musixiang within Yili, associated mainly with inorganic matter in coals of eastern and southern Junggar, and related to organic and inorganic matters in coals of other places in Xinjiang. The concentrations of cobalt in these coals are controlled by the groundwater table in swamp and the properties of parent rocks in the source area.