How do you say this girl is a rockstar in Chinese?

There isn't a direct translation for "rockstar" in Chinese that captures the same cultural connotation as in English. However, here are a few ways you could say "this girl is a rockstar" in Chinese, depending on the context and the specific meaning you want to convey:

General Praise:

* 她是一个摇滚巨星。 (Tā shì yīgè yáoɡǔn jùxīng.) - This literally means "She is a rock star."

* 她太厉害了！ (Tā tài lìhai le!) - This means "She is so amazing!"

* 她很有才华。 (Tā hěn yǒu cáihua.) - This means "She is very talented."

* 她真是个奇才。 (Tā zhēnshi gè qí cái.) - This means "She is truly a genius."

Emphasis on Confidence and Charisma:

* 她很有魅力，很有自信。 (Tā hěn yǒu mèilì, hěn yǒu zìxìn.) - This means "She is very charming and confident."

* 她很酷，很有个性。 (Tā hěn kù, hěn yǒu gèxìng.) - This means "She is cool and has a strong personality."

Emphasis on Talent and Success:

* 她在她的领域里非常成功。 (Tā zài tā de lǐngyù lǐ fēicháng chénggōng.) - This means "She is very successful in her field."

* 她是一个非常有天赋的艺术家。 (Tā shì yīgè fēicháng yǒu tiānfù de yìshùjiā.) - This means "She is a very talented artist."

Ultimately, the best way to say "this girl is a rockstar" in Chinese will depend on the specific context and the qualities you want to highlight.