A new identification method of cat-eye target from diffusion reflective background by scanning the coherently combined array Gaussian beams is proposed. The mathematical model of coherent combination of array Gaussian beams is established．By using Collins diffraction integral formula and method of expanding the aperture function into a finite sum of complex Gaussian functions, approximate analytical formulas for coherently combined array Gaussian beams passing through a cat-eye target and a Lambert diffusion reflective target are derived, respectively. Through numerical calculation, effects of array number and target size on the characteristics of the time distribution of the reflected light are studied. It is found that there is no periodic charasteristics in the time distribution of the Lambert diffusion reflective light, and the time distribution width increases along with the increase of the target size. The periodic characteristics of the time distribution of the cat-eye reflected light are similar to those of the y-axis distribution at the position of the target, and the lost frequency charasteristics increase along with the increase of the aperture size of the cat-eye target. So the cat-eye target can be identified from complicated diffusion reflective background easily and quickly, and the size of the diffusion reflective target or the cat-eye target can be estimated.