The pyrolysis behavior of Dagang slurry oil (DG-SO), Qingdao vacuum residue oil (QD-VR) and Canadian oil sand bitumen (CA-OB) were investigated by thermogravimetric mass spectrometry. The pyrolysis kinetic parameters were obtained by Friedman method, FWO method, and distributed activation energy model (DAEM), respectively. The results showed that DG-SO with relatively high content of saturates and aromatics had the highest pyrolysis reactivity, while QD-VR with relatively high content of resins and asphaltenes had the lowest pyrolysis reactivity. The releasing curves of H2, CH4, CO, and CO2 correspond to the main reaction temperature ranges of heavy oil pyrolysis. The distinctions of the shape, intensity and temperature range of the pyrolysis gases releasing curves between different types of heavy oils were mainly attributed to the corresponding composition and pyrolysis reactivity of each type of heavy oil. It was clearly found that Friedman method could gain more accuracy for description of pyrolysis process of heavy oil compared with FWO method in terms of equal conversion methods. The average activation energies (Ea) of DG-SO, QD-VR, and CA-OB were 80.15, 177.00, and 174.56 kJ/mol within the conversion range of 0.1~0.9, respectively. The one-component Gaussian DAEM could describe the whole process of SARA (saturates, aromatics, resins, asphaltenes), and their Ea were 107.78, 210.88, 268.75, and 285.44 kJ/mol, respectively. The four-component Gaussian DAEM could be used to precisely describe the whole pyrolysis process of heavy oil, and the calculated weighted average activation energies were 148.92, 205.92, and 190.37 kJ/mol, respectively. By comparing the Ea of QD-VR and its SARA components, it was found that the interaction between the SARA during the pyrolysis of heavy oil leaded to the Ea of QD-VR close to the Ea of aromatics in heavy oil. At the same time, it was found that the presence of resins and asphaltenes increased the average activation energy of saturates and aromatics, while saturates and aromatics reduced the average activation energy of resins and asphaltenes.