Accurate numerical simulation results of turbulent combustion are crucial for combustion organization and performance prediction studies of rocket-based combined cycle engine. However, there are few relevant lightweight chemical kinetic mechanisms available for kerosene. In this study, the two different kerosene detailed mechanisms were reduced, and six kinds of skeletal mechanisms were obtained, namely: 59 species/410 reactions (abbreviated as 59s/410r), 38s/180r, 27s/98r, and 64s/460r, 36s/191r, and 21s/70r. In order to validate the accuracy of the reduced mechanisms, these mechanisms were firstly validated in the ideal zero-dimensional constant-pressure reactor. The mechanism’s fidelity was validated under the following conditions: pressure of 0.1-0.3 MPa, ignition initial temperature of 1200-2500 K, and equivalence ratio of 0.6-1.5. The results for the ignition delay time, laminar flame speed, adiabatic flame temperature, and the evolution of main species are consistent with those obtained from the detailed mechanism. Additionally, the simulation of turbulent combustion in the combined engine was performed using the reduced 27s/98r skeletal mechanism and the 11s/10r global reactions with optimized kinetic parameters. The numerical simulation results are validated, analyzed, and compared with the ground experiment data.