A method for reconstructing a PET multi-bed image is provided, which may be applied to a PET scan having an axial overlapping region existed between every two adjacent beds. According to an example of the method, a combined set of PET projection data for at least two beds may be obtained by combining a set of PET projection data for at least two successive beds together in such a manner that two sets of PET projection data corresponding to an axial overlapping region between every two adjacent beds are added up. And then, a PET image for at least two beds may be reconstructed based on an image reconstruction iteration model and the combined set of PET projection data for the plurality of beds.