Abstract: Aiming at the problem of medium parameter estimation around buried objects, a method of medium parameter estimation based on image entropy is proposed. Firstly, the point spread function (PSF) of frequency diversity array ground penetrating radar (FDA-GPR) in medium is derived, and the relationship between PSF and back projection imaging algorithm is analyzed. Then, the imaging results of FDA-GPR and UWB-GPR are compared and analyzed. For the same region containing the target to be imaged, the medium parameters have a great influence on the propagation velocity of electromagnetic wave. When different medium parameters are used to image the region, the imaging results are also different. The image entropy of the imaging results under different parameters is calculated. The smaller the image entropy of the imaging results, the better the focusing degree of the imaging, and the closer the corresponding medium parameters are to their true values. The experimental results show that: when the conductivity of the medium is not zero, FDA-GPR has better performance in target location and imaging than UWB-GPR, and when the target is a slender target, the proposed parameter estimation method can effectively estimate the parameters of the medium around the target.