Abstract: Based on the comparative studies of three series of coal samples i.e., the Palaeozoic marine-influenced coal and terrestrial coal, and the Mesozoic terrestrial coal, the coal petrology and the content properties of C, H, O, N and other elements in Southwest region are explored. A viewpoint that the caking property of Mesozoic coal is not weaker than that of Palaeozoic ones, Provided that the coalification degree is proper, is presented for the first time.