It's wired that Qt Creator didn't have a syntax highlight for its own style file format , or did i missed some packages ?
VER: Qt Creator 2.1.0
I could not find any evidence in Qt's documentation that .qss is an officially designated file extension. I'd say just change it to .css.
Go to
Tools > Options > Environment > Mime types
Find text/css and add *.qss to patterns.
来源：https://stackoverflow.com/questions/7624656/no-syntax-highlight-for-qss-file-in-qt-creator