Techniques manage stripes in a storage system. A balance index of a storage device in the storage system is determined respectively, the balance index indicating a relationship between distribution of a set of stripes involved by the storage device and distribution of a set of stripes involved by storage devices in the storage system. A source storage device is selected from the storage devices according to the determined balance indexes. A source extent is selected from a set of extents that have been allocated in the source storage device. Data in the source extent is moved to an idle extent in a destination storage device in the storage devices. The extents in the stripes may be distributed as evenly as possible in the storage devices, thereby ensuring load balance of the storage system and managing the stripes in the storage system in a more effective manner.