The combustion of fossil fuels is the main form of energy supply in today's society, but with the depletion of fossil fuels, it is urgent to develop new alternative fuels. n-Dodecane is one of the important components of aviation kerosene, and also an important component of various alternative fuels for aviation kerosene. Laminar combustion characteristics of n-dodecane/air flames were investigated using CHEMKIN/PREMIX, providing a theoretical reference for the development of alternative fuel aviation kerosene. The initial temperatures were set as 400, 403, 423, and 470 K, the initial pressures were set as 0.1, 0.2, 0.3, 0.5, and 1.0 MPa, and the equivalence ratio was set as 0.6~1.6. This study mainly focused on the combustion characteristics of flames, temperature sensitivity analysis, and the distribution of intermediate free radicals. The laminar burning velocity (LBV), adiabatic flame temperature (AFT), net heat release rate (NHRR), and rate of production (ROP) of free radicals were obtained with the increase of initial temperatures and pressures. The results showed that the simulation values of LBV can well-predict other experimental values, whose trend was consistent with other models. The peaks of AFT appeared near the stoichiometric ratio. Similar to other hydrocarbon fuels, the most sensitive reaction was R1 (H+O2?O+OH) in the oxidation process. It was verified that there was an obvious spatial difference between the flame front and fuel pyrolysis through ROP analysis and the distribution of mole fraction. The increase in initial pressures reduced the reaction zone and accelerated the formation rate of free radicals. Laminar premixed combustion characteristics of n-dodecane/air flames were studied using Jetsurf 2.0 mechanism, and the effect of elevated temperatures and pressures was comprehensively discussed. The numerical results can enrich the basis of data at high pressure, which provides a reference for looking for alternative fuels for aviation kerosene.