The invention discloses a method and device for storing data. The method specifically comprises the steps of obtaining key value pair data to be stored; storing the key value pair data in pre-write log files of a disk; generating an index entry for the key value pair data in a memorizer according to the storing position of the key value data in the disk and keys in the key value pair data so as to execute preset operation on the key value pair data through the index entry, and writing the key value pair data reserved in a pre-write log file which satisfies a preset condition into the disk when the pre-write log file which satisfies a merging settling condition is detected, wherein the storing position comprises at least the file name of the pre-write log file and offset of the key value pair data in the pre-write log file and the initial position of the file. According to the method and device for storing the data, the problem of write amplification can be avoided, and the effectiveness of stored data is improved.