Abstract: Organic carbon as the main impurity contained in coal-series kaolinite exerts a great influence on loss on ignition of the kaolinite. In order to reduce the content of organic carbon in kaolinite, test is made on removal of the low-density organic carbon and other impurities with pneumatic cleaning method as the kaolinite and organic carbon differ in density. Test result shows that the low-density materials contain not only a lot of organic carbon but also a high proportion of calcium carbonate associated with organic carbon; and the use of pneumatic cleaning method can lead to not only reduction of content of organic carbon and hence decrease of loss ignition of kaolinite, but also drastic reduction of content of calcium carbonate in kaolinite.