Hi ​@Longlong  Welcome to Box Community!

If you are collaborating on a Box file/folder owned by someone, and a file has a link that is set to expire, please reach out to the owner if you need to extend your access after the expiration date.

However, if you are the file/folder owner, you can change the expiration date, if your Box Admin has enabled that capability. Use the same procedure to change an expiration date as you did to set it originally.

For more details regarding shared link, please visit Shared Links Frequently Asked Questions.

Have a great day!