一经……就……yījīng…jiù…

Once / As soon as: 一经……就…… (yījīng…jiù…)

Meaning: Once / As soon as (formal)

Pattern

"一经……就……" is a formal written and journalistic structure meaning "once... then..." or "as soon as it undergoes..., ...".
"一经" (yījīng) consists of "一" (once/as soon as) + "经" (undergo/pass through), emphasizing that undergoing the action just once immediately triggers the result.
The second clause typically contains "就" or the more formal "便".
Important differences from "一旦…就…": (1) "一经" applies to objective events that have already occurred or will inevitably occur by rule, whereas "一旦" is used for future hypothetical warnings; (2)

1
这种产品一经推出，就受到广大消费者的欢迎。
Zhè zhǒng chǎnpǐn yījīng tuīchū, jiù shòudào guǎngdà xiāofèizhě de huānyíng.
Once launched, this product was warmly welcomed by consumers.
2
这本小说一经出版，便引起了轰动。
Zhè běn xiǎoshuō yījīng chūbǎn, biàn yǐnqǐle hōngdòng.
As soon as this novel was published, it caused a sensation.
3
案件一经查实，相关人员将被严肃处理。
Ànjiàn yījīng cháshí, xiāngguān rényuán jiāng bèi yánsù chǔlǐ.
Once the case is verified through investigation, the relevant personnel will be dealt with strictly.

•Usually collocates with disyllabic procedural verbs (发现, 查实, 推出, 出版); the second clause requires 就 or 便.

⚠️ Common Mistakes:

•Using 一经 with uncertain hypothetical actions: use 一旦 or 如果 instead.

•Following 一经 with a stative verb: abounded action/procedural verb must be used instead.

•Omitting 就/便 in the second clause: makes the correlative structure incomplete.

Combine Vocabulary, Grammar, Reading Practice, Listening, Hanzi Writing, and Mock Exams at HSK 6 to master all skills together.