Rapid high-prescion determination top soil water content is of vital importance to precise agriculture , precise water resource management and the control of slope land erosion. The technology of low-frequency ground penetrating radar (GPR) currently in use is far from the requirement in precision for determination of topsoil water conteng. It is, therefore, essential to develop and adopt a high-precision detection technology. In this paper, the technology of high frequency (1 GHz and 2 GHz) Ground Penetrating Radar(HFGPR) was tested to determine topsoil water content in a vegetable field of silty clay loam in soil texture in Jiangning of Nanjing, China. HFGPR was used to determine topsoil water content of farmlands under different soil water content, GPR data and images were obtained and electromagnetic spectrum characteristic parameters extracted for analysis of their quantitative relationships with soil water content. Results showed that: The decision coefficient R² of ε~θ model in fitting the soil dielectric constant (ε) obtained by the 1GHz and 2GHz frequency GPR with the soil moisture(θ) measured in the field was 0.94 and 0.97, respectively, which demonstrates that the technology of high frequency GPR is feasible be applied to determine the soil water content in the topsoil of vegetable fields of silty clay loam soil. The new technology is much higher than the old one in precision in determining soil water content in topsoil layers.