千钧一发

Traditional (Taiwan): 千鈞一髮

On the HSK 7-9 vocabulary list, at CEFR level C2.

qiānjūnyīfà ㄑㄧㄢㄐㄩㄣㄧㄈㄚˋ

- a thousand pounds hangs by a thread (idiom)
  lit.
- (at the) critical perilous (moment)
  fig.

Character by character

Sources