In this paper, the issue of volume scattering overestimation as all known existing in Freeman decomposition is analyzed in detail, and a three-component decomposition model based on de-orientation and a generalized volume scattering model is presented to reduce the overestimation of volume power. Firstly, de-orientation is applied to the covariance matrix to reduce the volume scattering power before it is decomposed into three scattering components. Secondly, a generalized volume scattering model is adopted by considering the change of HH and VV ratio in different forest areas. In addition, power constrain method is added to eliminate negative power completely. The results are validated by using the L band ESAR data in Oberpfaffenhofen area in Germany and comparing with many other methods. The results show that the integrated model can solve the volume scattering overestimation more notable than other decomposition model, and the results are closer to real scattering type.