喜出望外

xǐ chū wàng wài

overjoyed at an unexpected good thing

Character by character

喜xǐ
joy

出chū
goes

望wàng
hope

外wài
beyond

收到录取通知，他喜出望外。

He was overjoyed when his acceptance letter arrived.

Tone: positive (praise).

For a happy surprise beyond what you hoped, not for joy you were expecting.

Learn it in context

This idiom and thousands more are in Learn Chinese with Bao, with audio, pinyin and drills that make them stick.