The introduction of polarimetry to SAR interferometry makes it possible to improve the interferometric measurement resolution of the under-vegetation terrain and to estimate the height of vegetation targets. This paper introduces a new algorithm of polarimetric SAR interferometry

which can greatly improve the precision of the measurement. The coherent model of vegetation is used as the input of the polarimetric interferometric SAR system to get the simulation data

and the data is used to analysis and test the presented algorithm.