The invention discloses a processing method of file data of an NAS cluster system and an NAS cluster system. The method comprises the following steps that: before a client needs to execute file establishment, corresponding storage devices are determined by using an HASH algorithm; storage information of a plurality of storage devices corresponding to the client is analyzed; and on the condition that the file storage space demand is determined to be satisfied, files are established at corresponding storage devices in a priority storage device order of local storage devices corresponding to the client, the corresponding storage devices determined by file HASH values, and storage devices in a cluster storage device list. On the basis of the storage device selection strategy, because the local storage way is used whenever possible, occupation of network resources during reading and writing can be avoided; and file searching can be carried out conveniently. According to the invention, with the processing method and the NAS cluster system, the data flow based on network transmission is reduced, the network load is reduced, and the I/O processing efficiency of the NAS cluster system is improved.