translate into English: 保持冷静的头脑

keep the mind calm

Her head was on fairly straight.
她却有一颗还算冷静的头脑。

Anyway, I hope he keeps his head, and I'm rather inclined to think he will.
不管怎样，我希望他保持冷静的头脑，我想他会的。

keep a calm mind
keep your mind calm

或用短语keep the presence of mind
(较推荐）

Keep your mind stay calm

keep the calm mind

keep your mind clear