@Xiaoyun Liao You can't select disks as resources to be moved across regions. However, disks can be moved as part of a VM move or by creating and copying an Incremental snapshots of a disk.
Below steps how to move standalone (not attached) disks between regions.
1. Create an incremental snapshot for managed disks
- Sign into the Azure portal and navigate to the disk you'd like to snapshot.
- On your disk, select Create a Snapshot.
- Select the resource group you'd like to use and enter a name.
- Select Incremental and select Review + Create
- Select Create
2. Copy an incremental snapshot to a new region
- Select Copy snapshot.
3. After snapshot created, allow some time for the copy operation to complete and process with the disk creation.