A demodulation principle and system for the multi-channel multiplexed Fabry-Pérot fiber-optic accelerometers in parallel based on a Fizeau interferometer are proposed,and the Fabry-Pérot fiber-optic accelerometers are based on the principle that the acceleration can be sensed through changing the length of the Fabry-Pérot cavity by the inertial mass. The function of the relative output intensity from the Fizean interferometer with the Fabry-Pérot cavity length of the accelerometers and the wedge thickness of the Fizeau interferometer is established. Furthermore,a theoretical acceleration model for the multiplexed Fabry-Pérot fiber-optic accelerometers based on Fizeau interferometer is also established. On these bases,the demodulation and multiplexing principle of the multiplexed Fabry-Pérot fiber-optic accelerometers based on the Fizeau interferometer are numerically simulated and the multiplexing capacity is analyzed. The research results indicate that the numerical results are consistent with the theoretical analysis and the accelerometers are feasible.