热火朝天

rè huǒ cháo tiān

in full swing; buzzing with energy

Character by character

热rè
hot

火huǒ
fire

朝cháo
towards

天tiān
sky

工地上热火朝天，工人们日夜赶工期。

The building site is in full swing, with crews working day and night to meet the deadline.

Tone: positive (praise).

朝 is cháo (towards) here, not zhāo. A favourite of 1950s–70s reports on collective work; today used of any lively bustle: 大家讨论得热火朝天.

Learn this in Lesson 83 · HSK 6–7: 新中国的头三十年 (New China’s first thirty years, 1949–1978)

A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.