The instantaneous frequency is an important feature of GPR image and signal. However, the traditional method either cannot realize the instantaneous frequency extraction in real sense or can only apply for narrow-band signal. The HHT method can extract intrinsic model function (IMF), and then combines Hilbert transfer to get the instantaneous frequency which can represent the time-varying frequency of the non-linear and non-stationary signal. In this article, the experiment is tested on B-scan GPR data, the result shows that the instantaneous frequency based on HHT can effectively represent the object and avoid the directive wave.