Hello, Fengyun -
Have you checked to make sure the thermal printer paper is loaded correctly?
See this YouTube video:
https://www.youtube.com/watch?v=QfhNqWsR30E&index=30&list=PLEYEHgqj6R-bj_-12st8J4CdUyvUd5czq
Another possibility is that the paper cutter is locked. Check the manual for the printer, Page 21, regarding this.
In case you do not have the manual for the printer, you can download it here:
http://www.starmicronics.com/support/Mannualfolder%5Ctsp100en_hm.pdf
It is a PDF document, so you will need Adobe Acrobat Reader software (free.)
Best wishes.