The present invention provides a method, an apparatus, and a system for controlling quality of service of a storage system. The method includes: identifying a target data object; acquiring a storage address of the target data object stored in a storage device by searching a file system of the host, wherein the file system contains data mapping the data object to the storage address of the target data object; and sending the storage address to the storage device to instruct the storage device to perform quality of service control on access to the target data object at the storage address. The present invention solves the problems of resource waste and lower quality of service in a QoS control manner, and can satisfy user requirements more accurately.