The present invention provides a file update method for separate storage of network information, comprising the following steps: splitting and saving the file, uploading the cloud-separated data block to the cloud after splitting the file; uploading judging step, judging whether the cloud-separated data block is successfully uploaded Go to the cloud, if so, jump to the local saving step, otherwise jump to the step of judging the modification record file; the local saving step, store the local data block and delete the existing modification record file; judge the modification record file step, judge whether there is a modification Record the file, if so, update the modification record file, if otherwise, generate the modification record file, and then jump to the step of modifying the record file; modify the record file step, encrypt and save the modification record. When the invention generates or updates the modification record file, information such as the key required for the encryption transformation operation is extracted from the original cloud-separated data block, and the separated storage protection of the file content can be completely maintained even when there is no network update.