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Lop Nur is a famous dried up lake in Xinjiang Province of northwest China and finally lost its last drop of water in 1960 s. It is well known for its "Ear" feature in optical remote sensing images. Likewise, the "Ear" feature is shown in Synthetic Aperture Radar (SAR) images, and even larger because of penetration effect for SAR signals. That is to say, SAR is capable of detecting subsurface targets and materials. The objective of this paper is to analyze the volume scattering mechanism of subsurface and reveal the genesis of Lop Nur "Ear" feature with full polarimetic SAR images. Two field investigations were conducted in 2006 and 2008 in order to validate the image interpretation and calculation results. In this study, the scattering physical mechanisms are discussed based on the results of field investigation. A suitable volume scattering model is used to simulate the contribution of volume backscattering to a certain extent. Meanwhile, ALOS PALSAR images for Lop Nur were collected, and the SAR Cloude decomposition method was used to extract the volume scattering components, based on which the developed volume scattering model was validated. The root mean square error (RMSE) of horizontal and vertical polarization are 1. 62% and 1. 68% representatively, and the fitting effect is relatively good. According to the parameters analysis of the model, it is found that salinity at subsurface is the genesis of "Ear" feature, which is strongly correlated with Lop Nur evolution.