A data processing method and a device in a distributed file storage system, where the method includes receiving, by a client agent, a data processing request which carries a file identifier, an offset address, a file length, and other information of a target file; obtaining, by the client agent, redundancy information according to the file identifier carried in the data processing request, where the redundancy information includes a quantity of data strips, N, of the distributed file storage system and a quantity of parity strips, M, of the distributed file storage system; determining a quantity of valid strips, DSC, of the target file according to the offset address and the length information; determining a quantity of actual strips, N′, of the target file according to the DSC and the M; and determining corresponding strips according to the N′ and processing the corresponding strips.