Some reference are so important and interesting，I want to mark those references with striking symbols or color.
would Endnote provide the functionality？
No, - you can put something in an unused field that you can search on, or make a smart group so you can select them automatically, and show the files in the the library display (edit preferences,> display fields. But you can’t bold them or make them fluorescent Green.
(but you can always make a suggestion in the suggestion forum or online at http://www.endnote.com)