A simple mathematical model is set up to investigate the effect of platform vibration on the image quality in an airborne strip-mode synthetic aperture ladar (SAL) based on the work of Park. Numerical simulation is carried out to show the influence of the vibration parameters such as amplitude,frequency,initial phase,or peak acceleration,on the SAL image resolution within the frequency range of 0-500 Hz. SAL image of ideal point target or extended surface target with or without vibration is given. The simulation results show that the quality of SAL image is most correlated to the peak acceleration of the platform vibration. With higher acceleration,the SAL image deteriorates severely. As illustrated in the simulation,the SAL image is acceptable as the peak acceleration is no more than threshold and will be totally distorted in the azimuth with many ghosts as the acceleration is greater than another threshold. In addition,the simulation results also indicate that initial phase of the vibration plays an important role in deterioration of the SAL image induced by the vibration.