The pyrolysis characteristics of Eucommia ulmoides Oliver leaves untreated and treated by biological fermentation were investigated using thermogravimetric analysis. The derivative thermogravimetry curves, kinetic characteristics, and activation energy of the samples were significantly different from other biomass. The average activation energies (253.40 and 268.77 kJ/mol, 257.71, and 270.82 kJ/mol) were close almost similar to that obtained from Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa methods and were higher due to the presence of gutta-percha. Meanwhile, the decomposition and kinetic characteristics could be changed by fermentation technology. Besides, Coats-Redfern revealed that second-order model (f(alpha) = (1-alpha)(2)) could be used to better describe the decomposition mechanism of these samples.