Abstract: Pyrolysis of cornstalk was studied by using STA449c thermogravimetric apparatus with the heating rates of 5, 10, 15, 20, 30 K/min and final temperature of 1273 K. The pyrolysis process of cornstalk includes three steps: losing water and pre-pyrolysis, main pyrolysis and carbonization. As the heating rate increased, the maximum pyrolysis rate increased greatly, and the characteristic temperature became higher and the DSC curves sloped down. When heating rate was too fast, dehydration process was lagged behind. The activation energy, calculated by both integral method and differential method, was (161±23) kJ/mol. With Malek method, it could be determined that pyrolysis process of cornstalk accorded with the J-M-A equation, which indicated that pyrolysis mechanism of cornstalk is random nucleation and later growth. The experimental data were simulated using MATLAB software, and the mechanism was further confirmed, finally the kinetic parameters of cornstalk pyrolysis were determined.