Abstract: With the expansion to the deep strata for the exploration of marine oil and gas in the Tarim Basin, the upper limit of temperature for the occurrence of ultra-deep reservoirs has become a scientific concerning of organic geochemistry and petroleum geology. Thermal simulations of the ultra-deep Ordovician oil from well SB 7 in the North Shuntuoguole area of Tarim Basin were carried out using a gold-tube confined system under two different pressures of 50 and 90 MPa and two different heating rates of 2 and 20℃/h, respectively. According to the results of simulation experiments, Kinetics software was used to calculate the chemical kinetics, and the mass yield of gas generation during oil-cracking under different temperature and pressure conditions was compared, and its geological significance was discussed. Under different temperature and pressure stages, the same oil sample experienced a similar process of oil-cracking as well as of total volume and mass yield of gas generation. Heavier gas compounts were generated in the early stage of oil-cracking and further transformed to form methane in the later stage. Heating rates impacted greatly on oil-cracking processes. Under a higher heating rate, the oil-cracking process moved to higher temperature and the separate oil phase can be kept with a higher temperature limit. High pressures only played minor roles on oil-cracking. With the same heating rate, higher pressure negligibly suppressed oil-cracking in the early stage of oil-cracking, whereas in the later stage, higher pressure promoted oil-cracking a bit. The difference of oil-cracking process under different temperatures and pressures can be explained by the distribution of activation energy. The distribution of activation energy of C₁-C₅ gas mass yield of oil-cracking of well SB 7 is relatively more concentrated, suggesting that the "temperature window" of oil-cracking is relatively narrower. According to the thermal simulation and kinetics calculation results, the maximum temperature of oil phase in the block 1 in the North Shuntuoguole area is greater than 180℃, and oil phase can be maintained at a depth greater than 9 000 m.