A method and device for Fail Bit (FB) repairing. The method includes: a bank to be repaired of a chip to be repaired is determined; first repair processing is performed on first FBs in each target repair bank using a redundant circuit; second FBs are determined, and second repair processing is performed on the second FBs through a state judgment repair operation; for each target repair bank, unrepaired FBs in the target repair bank is determined, and candidate repair combinations and candidate repair costs of the unrepaired FBs are determined using an optimal combined detection manner; and a target repair cost is determined according to the candidate repair costs, and a target repair solution corresponding to the target repair cost is determined to perform repair processing on the unrepaired FBs according to the target repair solution.