Aspects of the disclosure provide methods and apparatuses for storing service data. In some examples, an apparatus for storing service data includes processing circuitry. The processing circuitry receives service data of a user and determines, in a plurality of blockchains, a target blockchain according to a user attribute of the user. Based on the service data and an eigenvalue of a block header of a first block in the target blockchain, the processing circuitry generates a second block in the target blockchain. The first block is a previous block of the second block. The second block is used for recording the service data.