The invention discloses a data determination method applied to a distributed storage system and a distributed storage system. The distributed storage system comprises a plurality of processing units and a plurality of storage units corresponding to each processing unit. A processing unit corresponding to a storage unit storing preset data is designated as a first processing unit, a storage unit storing the preset data in the first processing unit is designated as a first storage unit, and a storage unit other than the first storage unit in the first processing unit is designated as a second storage unit. According to the data determination method provided by the invention, it is determined whether preset data needs to be encrypted, and if so, the preset data is encrypted, such that privacy protection is performed only on preset data that needs to be encrypted rather than on all data, thus achieving reasonable data usage.