In this work, a reduced n-decane/alpha-methylnaphthalene/polycyclic aromatic hydrocarbon (PAH) kinetic mechanism for calculation of combustion and soot behavior of diesel and its surrogate fuel was developed. This mechanism consists of the pyrolysis of n-decane (C10H22) and a-methylnaphthalene (C10H7CH3), C-0-C-3 core species reaction, and the formation of initial benzene and PAHs, including 77 species and 287 reactions. The pyrolysis reaction of fuel was obtained by pathway analysis from a detailed mechanism, while the reactions of core species and PAHs were reduced by a directed relation graph with error propagation, computational singular perturbation method, and direct sensitivity analysis, sequentially. The mechanism was validated by the mole fraction of main species and key PAH species in the ethylene premixed flame, ignition delay times of pure and mixed fuel in shock tubes, and the concentrations of major species in jet-stirred reactors. Finally, the new developed mechanism was coupled with a soot phenomenological model, where A4 was employed as the precursor in soot inception, and a multi-dimensional turbulent model, to calculate the combustion and soot emission processes in a diesel engine. The pressure in the cylinder, apparent heat release rate, and normalized soot fraction were obtained in this calculation. Both the fundamental modeling and engine modeling agree well with the data from the literature.