Tā xiōngzhōng yǒu qiūhè, zuòshì cóng bù huāngluàn.
She has a clear plan in her mind and never acts in a fluster.
Tips
usage
胸中 is a literary expression meaning 'in one's chest / mind / heart'. It often appears in formal or poetic contexts: 胸中有数 (knowing what one is doing), 胸中有丘壑 (having a grand vision).