In this paper, the X-band coherence statistical characteristics related to the height of ambiguity and polarization of two typical forested areas is investigated, using X-band multibaseline polarimetric InSAR data acquired by an automobile-based InSAR system. Furthermore, according to the analysis of the coherence statistical characteristics of the experimental data, we propose an empirical model in relation to the height of ambiguity, polarization and forest height, which can be used as a reference for InSAR baseline configuration in forest mapping and forest height inversion based on multibaseline InSAR data.