A method for phase unwrapping is provided. The method may include obtaining an initial phase image including a plurality of phase elements. At least one of the phase elements may be wrapped. The method may also include generating a phase mask by preprocessing the initial phase image based on phase differences between the plurality of phase elements. The method may also include generating at least two segmental phase images by segmenting the initial phase image along at least two directions based on the phase mask. The method may further include generating at least two intermediate phase images by performing phase unwrapping on each of the at least two segmental phase images, respectively. The method may further include determining an unwrapped phase image corresponding to the initial phase image based on the at least two intermediate phase images.