The present application relates to a system and method for iterative reconstruction. The system and method may acquire raw data detected by the imaging device from at least one angle; a first sub-image may be generated by performing a filtered back projection on the raw data; the first air mask may be determined by performing a minimum value back projection (BP) on the raw data; and based on the first sub-image, the first air mask and the raw data can reconstruct at least one image by performing iterative reconstruction.