Abstract: The signal processing commonly relies on the vibration controller or the COLA (constant output level adaptor) data acquisition system in the sine vibration test for the manned spacecraft. For the mechanical parameter measurement system without the COLA function for the manned spacecraft, the traditional STFT(short time Fourier transform) method can result in a spectrum leakage due to the asynchronous sampling, thus the amplitude of frequency domain might be reduced and a major error might be produced. To solve the above problem, a data processing method based on the band pass filter in the frequency domain is proposed. The maximal values of the frequency components of the signal can be acquired by moving the center frequency of the band pass filter, and the spectrum analysis of the mechanical parameter measurement system in the sine vibration test for the manned spacecraft is acquired by the proposed method. It is shown that the proposed method can effectively acquire the spectrum at each measuring point of the mechanical parameter measurement system and the influence of the spectrum leakage by the traditional STFT method can be reduced. The research findings provide a reference for the signal processing method of the sine vibration test for the data sampling system independent of the vibration controller and without the COLA data acquisition system.