Abstract: The output of detector which receives the interference light that is modulated by photoelastic modulated interferometer is weak electric signal that is of rapid change. Extracting and amplifying this electric signal is crucial to the development of the photoelastic modulator-Fourier transform spectrometer. A photoelectric conversion amplifying circuit with high signal-to-noise ratio and high bandwidth was designed through analyzing the interference light. The circuit consists of power circuit, photoelectric conversion circuit, amplifying circuit and the band-pass filter circuit with the theoretical pass band of 100 kHz ~ 3.5 MHz. The test results indicate that the circuit can amplify the signal from the detector whose maximum frequency is 1.6 MHz to about 670 mV, extract and amplify the output signal effectively from the background noise, and provides reliable data to the subsequent Fourier transform.