It is well known that the process of oil shale pyrolysis is extremely complicated, for several competing or parallel reactions occur simultaneously, and various products are continuously generated, serving as new reactants. In this work it is assumed that there occur two parallel reactions in the devolatilization of organic matter, one represents the volatilization of bitumen and the other represents the pyrolysis of kerogen. Kinetic triplets for the competing or parallel reactions are different from each other. To investigate the pyrolysis mechanism of Jimsar oil shale of Xinjiang Province, China in more detail, the bi-Gaussian distribution method, a multi-stage parallel reaction model and two master plots methods are adopted to determine the kinetic models in this work. The apparent activation energy (E) is calculated by the Flynn-Wall-Ozawa (F-W-O), Kissinger-Akahira-Sunose (K-A-S) and Friedman methods. According to the results, it can be concluded that heating rate exerts little influence on the kinetic parameters but has some impact on the pyrolysis process as a whole. The results of this work reveal the pyrolysis characteristics of oil shale to a certain extent.