Vegetation water content (VWC) is an important parameter of agriculture and forestry. In this letter, specific polarization ratios were evaluated for estimating VWC of corn and soybean. Backscattering coefficients (σ_hh, σ_vv, σ_vh and σ_hv), polarization ratios (σ_hh/σ_vv,σ_vv/σ_vh, and σ_hh/σ_hv), and the radar vegetation index derived from L-band (1.26 GHz) and S-band (3.15 GHz) radar data of the passive and active Land S-band sensor (PALS) in Soil Moisture Experiments 2002 were implemented to develop various linear relationship models with field VWC measurements for corn and soybean, respectively. L-band σ_hh/σ_vv was found to be most correlated with corn VWC (R = 0.81), while for soybean, L-band σ_hh/σ_hv was the best parameter to estimate VWC with an R of 0.90. Based upon these analyses, prediction equations for the estimation of corn and soybean VWC using the polarization ratios were developed. Results indicated that L-band σ_hh/σ_vv was able to estimate corn VWC with a root mean square error (RMSE) of 0.53 kg/m² and a mean absolute relative error (MARE) of 11.48%. As for soybean, L-band σ_hh/σ_hv was capable of estimating soybean VWC with an RMSE of 0.12 kg/m² and an MARE of 13.33%. The main reason for these differences is most likely due to the disparate structure features and VWC distribution of corn and soybean. This letter proposes an effective method for acquiring VWC in regional areas, and it is also considered to be a powerful supplement for the current methods based on optical remotely sensed data.