A method for processing a write request is disclosed, the method includes: determining, by an IO scheduler, that current IO scheduling is in a blocked state; selecting, by the IO scheduler, a target synchronous write request from to-be-processed IO requests; adding, by the IO scheduler, an acceleration flag to the target synchronous write request, where the acceleration flag is used to instruct a flash memory controller to perform acceleration processing on the target synchronous write request by using idle space of a flash memory; after the flash memory controller receives, from the IO scheduler, the target synchronous write request, determining, by the flash memory controller, a size of the idle space of the flash memory; and when the size of the idle space of the flash memory is greater than a threshold, performing, by the flash memory controller, acceleration processing on the target synchronous write request.