A three-wavelength quadrature phase compensation method for recovering non-periodic dynamic signals in an extrinsic Fabry-Perot interferometric (EFPI) sensor is proposed. The influence of the direct-current component is eliminated by using three interferometric signals, and two orthogonal signals are generated by the phase compensation algorithm to demodulate the signals to be tested. In the experiment, an aperiodic dynamic signal is loaded on the EFPI sensor, and three laser interferometric methods are used to demodulate the experimental data. The results show that the proposed method has higher demodulation accuracy, and is suitable for the high temperature environment with cavity length change and the measurement of non-periodic dynamic signals.