Abstract: By introducing the hybrid input-output algorithm into classical Fourier domain, the phase retrieval of 2-dimensional complex image in fractional Fourier domain is studied. The implementation of the algorithm is given in detail, and numerical simulation is also done. For fractional Fourier transform, these results reveal that the proposed algorithm works well for the orders between 1/2 and 3/2 in the orders from 0 to 2, but not satisfactory in other orders.