Methods, systems, and apparatus, including computer programs encoded on computer storage media, for blockchain-based file querying are provided. One of the methods includes: receiving a query request for a target file, the query request comprising identification information of a user and the target file; obtaining the target file based on the identification information of the user and the target file; providing a query page of the target file, the query page comprising interactive elements for selecting whether to upload the target file to a blockchain; receiving a user selecting to upload the target file to the blockchain; hashing the target file to generate a digital digest; signing the digital digest according to an asymmetric encryption algorithm using a private key associated with a cryptographic key pair to obtain a digital signature; and uploading the target file, the digital signature, and a public key associated with the cryptographic key pair.