High temperature simulation experiment by quartz cuvette technique and Fourier transform infrared spectroscopy (FTIR) was used for the study of the chemical structures of kerogen from the Early Jurassic coal in the J(1b) coal bed in Kekeya, Turpan-Hami Basin, Xinjiang at different temperatures. Combining the microscopic statistical results of macerals with the change of IR peaks and corresponding IR parameters with increasing simulation temperature, the hydrocarbon-generation characteristic and mode of the algae coal from Kekeya were estimated. The results indicate that the coals in question are a satisfactory kind of source rock for oil and gas, since their main component is desmocollinite and also contains some algae and many small sporogonium. As the temperature becomes higher and higher, the offshoots of the aromatic structure keep falling off. The heteroatomic compounds and aliphatic structure which have lower activation energy are gradually separated out, inducing that the hydrocarbon-generation potential of kerogen decreas. This process begins at 200 degrees C or so, bulges at 350 degrees C, and nearly comes to an end at 500 degrees C. What's more, kerogen tends to be graphitized after 500 degrees C-cores of aromatic structure aggregate and arrange more and more serriedly; this reaction looks quite obvious when it's heated to 600 degrees C.