The combustion experiments of oil shale semi-coke from Wang Qing retorts, cornstalk as well as their mixture were conducted under different heating rates using the thermogravimetric analyzer. The results showed that the advance ignition and burnout can be achieved when semi-coke was mixed with cornstalk. Derivative thermogravimetric curve of the experiment was compared with that of the calculated. The values of interaction index were solved. The interaction of mixture in the combustion process occurred mainly in 400-600 degrees C. It can be explained that the combustion of fixed carbon in cornstalk was delayed. The kinetics of combustion was studied for samples. The activation enthalpy, activation entropy and free energy of activation were analyzed by Kissinger-Akahira-Sunose equation and distributed activation energy model based on Eyring rate constant. The free energy of activation decreased with the addition of cornstalk proportion in the mixture. The results showed the feasibility using Johnson-Mehl-Avrami equation to simulate thermogravimetric curve. The representation of free energy of activation simulated agrees with that solved by Kissinger-Akahira-Sunose equation. (c) 2011 Published by Elsevier Ltd.