In this paper, we generalize the method proposed in [1] to solve the phase retrieval problem of spatial correlation functions in optical systems. A set of equations for determining the phase of the correlation functions is given. Using these equations and the iteration computing method, the phase of correlation functions can be determined. It can be shown that, if the transmission matrix K is unitary, in the coherent limit, the equations derived in this paper turn out to be that obtained in [1].