Abstract: Abstract: With the development of photoelectric technology, the photoelectric imaging devices with charge coupled device as its signal receiving component obtain an increasingly wide range of applications. The output signal of CCD is an analog signal, which mixed with all kinds of noise and interference. Among them, the white noise and 1/f noise are the most important factors affecting the signal to noise ratio of CCD device output signal. The conventional method is to make the CCD output signal pass through a low pass filter；but low pass filter can't effectively remove 1/f noise. To solve this problem, the band pass filter method based on the sinusoidal modulation of integration time is proposed in this paper. Then， the results of modelling and simulations in MATLAB show that the method proposed in this paper can remove 1/f noise and white noise effectively. In the actual spectral detection system, the proposed method has a strong practical value.