Synthetic Aperture Radar (SAR) Tomography extends the capability of SAR systems and allows reconstructing the height profile of observed scene. The deramping, one of important processes of SAR tomography, was investigated and a new deramping method based on simulated interferometric phase was proposed. This method can avoid extra atmosphere phase and obtain excellent deramping result using low precise elevation of the target, so it facilitates SAR Tomography. Finally, the validity and availability of this method is validated by the results obtained by processing real data.