Synthetic aperture ladar (SAL), whose carrier is laser, makes use of synthetic aperture processing to improve the resolution of images. Vibrations from the platform of SAL would have effects on the imaging quality of SAL because of the short wavelength of laser. Firstly, based on the paired-echo theory, the effects of angle vibration on the imaging quality are analyzed. Then, the amplitude and the position of the paired-echoes are deduced in detail. It was found that the vibrations would result in paired false target which cannot be eliminated by the traditional windowing method used in suppressing the side-lobes. Finally, the simulations prove the validity of the analysis. It provides theoretical foundation for analysis and design of SAL system.