把 + Object + 当成 + Noun
Reach for this when you want to say someone treats or regards X AS Y — 'take X to be Y.' The 把 marks the thing being categorized, 当成 ('to consider as / to treat as') makes the assignment. Useful for both literal mix-ups ('she took the salt for sugar') and figurative framings ('he treats me like family'). Conversational and idiomatic; the 当作 variant means the same thing in slightly more formal writing.
Structure
[SUBJECT] 把 [OBJECT] 当成 [NOUN/ROLE]
bǎ [OBJECT] dāngchéng [NOUN]
How to Think About It
把 isolates the thing being acted on; 当成 supplies the new identity it's being given. Together they say 'A acts on B by labeling it as C.' Drop 把 and the sentence still works (他当成我是朋友 sounds odd), but the structure feels less deliberate — 把 spotlights the object as the target of the categorization.
Examples
他把我当成了自己的弟弟。
Tā bǎ wǒ dāngchéng le zìjǐ de dìdi.
He treated me like his own younger brother.
别把工作当成生活的全部。
Bié bǎ gōngzuò dāngchéng shēnghuó de quánbù.
Don't treat work as the whole of your life.
她把这只小猫当成了家人。
Tā bǎ zhè zhī xiǎo māo dāngchéng le jiārén.
She treats this little cat like family.
Common Mistake
Learners forget that 当成 already contains 'as,' so they add 是 or 像 after it. 把 X 当成 Y is complete on its own — adding 是 breaks the structure.
他把我当成是朋友。
他把我当成朋友。
Don't Confuse With
把 + Object + Verb + Result
Generic 把 sentence where 当成 is replaced by any action verb ('把书放在桌上'). Use 当成 specifically for identity assignment, not physical actions.
把 + Object + 当作 + Noun
Near-identical meaning, slightly more formal. Use 当作 in writing; 当成 sounds more conversational.
把 + Object + 看作 + Noun
Similar meaning, but 看作 emphasizes the speaker's view ('regard as'), often used in opinions or evaluations rather than habitual treatment.
Practice
Fill in the blank: 他 ____ 我当成最好的朋友。
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把
Fill in the blank: 她把这本书 ____ 了宝贝。
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当成
Arrange into a sentence: 我 / 把 / 当成 / 这个 / 城市 / 第二个家
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我把这个城市当成第二个家。
Translate to Chinese: Don't take his joke as the truth.
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别把他的玩笑当成真的。
Use 把……当成…… to say how someone treats you or how you treat something.
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我的老师把每个学生都当成自己的孩子。
Hear It in Real Episodes
This pattern appears in 1 Fluentide episode: