Phase retrieval based on the transport of intensity equation (TIE) is a non-interferometric and quantitative technique for phase reconstruction which has been applied to many fields of physics. The TIE expresses the relationship between the object-plane phase and the axial intensity derivative in the Fresnel region for coherent and partially coherent fields and there have been many methods to solve it. In this paper, the Fourier transform method that was an approximate but a widely used solution to the TIE was studied. The concrete steps of the solution were given and two simulations were performed to study the influence of the intensity on the phase retrieval accuracy. Finally, a fiber was selected as the sample to reconstruct its phase using Fourier transform method in practice and the phase was retrieved with acceptable accuracy.