Wavelet extraction algorithm based on fractional Fourier transform is presented in this paper. The wavelet and GPR medium is descried as a time integral based on the assumption that GPR medium model is linear time-varying systems and the wavelet is unchanging during propagation. The optimal solution is found by searching p in the range of [-2, 2] to step 1/300. Finally, wavelet estimation signal in time-domain is obtained after an inverse fractional Fourier transform. The extracted wavelet from experiment GPR data shows that the wavelet extraction algorithm is valid.