The disclosure provides a processing method, device and system for data of a distributed storage system. The method includes: acquiring a first schema structure of target data and a second schema structure of source data; and processing the source data into structural data of the first schema structure according to the first schema structure and the second schema structure. The disclosure solves a problem that a data schema structure in a distributed storage system in related arts is inflexible to be described. There is a beneficial effect of improving description flexibility of the data schema structure so as to improve data processing efficiency.