An improved algorithm of phase generated carrier(PGC) demodulation for optical fiber interferometer sensors is proposed.When the amplitude of the phase disturbance is relatively small,the phase demodulation with this algorithm can be accomplished with the fundamental frequency mixing only,yielding a signal waveform proportional to the original one.Thus the efficiency of the whole demodulation process can be improved.The simulation and experimental results verify the feasibility of the proposed algorithm.In the signal detection experiment based on Mach-Zehnder interferometer(MZI) with the external modulation,the correlation coefficient between the demodulated signal and the original one is greater than 0.99.