The purpose of this application is to provide a method and device for backing up data. Specifically, read and detect whether the page of the data file has a page break problem; and lock the page with the page break problem into a readable and unmodifiable state, and re-read and copy the page to the backup set, and then release the page Locks the read-only, non-modifiable state of the page. Compared with the prior art, the method and device for backing up data described in the present application reads and detects whether a page of a data file has a page break problem, and uses a preemptive method to lock the page with the page break problem to be readable and unmodifiable. state to temporarily prevent subsequent data from continuing the writing process to the page. After the page quickly completes the writing process of the current data, the page is re-read and copied to the page in the backup set, so as to solve the problem well. The problem of page breakage in the backup process is eliminated, and the backup success rate is greatly improved.