Abstract: Based on the estimated polarimetric coherence matrices of the three different scattering mechanisms by Freeman decomposition, the polarimetric interferometric cross-coherence matrices could be simply modeled as a function of the vegetation height, the extinction coefficient and the topographic phase. Based on this model, a new optimization model is established. The target function of this new optimization model is the difference between the computed results of polarimetric interferometric cross-coherence matrices and their estimated results, the variables are the vegetation parameters. A new vegetation parameters inversion method based on the Freeman decomposition is proposed. Compared to three-stage inversion process, this new method does not need to estimate the volume correlation coefficient, so it could avoid the error of the estimation of the volume correlation coefficient and more importantly this new method supplies a new approach to the inversion of the vegetation height. The simulated PolInSAR data by the PolSARpro software is processed to validate the novel method.