Laser coherent detection has applied widely in the area of modern precise detection due to its high sensitivity and anti-disturbance property. The two-dimensional (2D) image information has more ability to reflect the property of the target. Therefore, the PCI8522 data asquisition (DAQ) card and the scanning galvanometer are combined together through analog trigger (ATR) trigger synchronizing for the purpose of receiving the Doppler frequency spectrum. The 2D frequency spectra are obtained for naked and camouflage net covered rotating diffuser, and the imaging size is 31 pixel×31 pixel. The Doppler frequency ranges from 3 MHz to 7MHz, and the target from the noisy background through the 2D frequency spectral image can be distinguished. The noise in the image processing is analyzed and the results are as follows: the area near the center axis of the target has large noise probability and the main reason is the frequency spectral gate with 200 kHz span. The other kind of noise comes form 5 MHz center frequency without Doppler frequency shift restricted by the frequency spectral gate, and there′s no need to wipe off this kind of noises because it is the background of the useful information. This research can be the basis of the application of laser coherent detection in the field of moving target camouflage discrimination.