"Peeping" or "snooping" through someone's diary in Engpsh is called "reading someone's diary without permission".

It comes from the verb "peep," which means "to look at something quickly and secretly" and the verb "snoop," which means "to look around a place or at something in a way that is not popte or is secret."

Example Sentences:

She felt violated when she caught her sister snooping through her diary.
He couldn't resist peeping at her diary when she left it lying on the table.
My pttle brother always reads my diary when I'm not home, it's so annoying.

中文翻译：

她被妹妹偷看日记时感到受侵犯。
他禁不住偷看她的日记，当她把它放在桌子上时。
我小弟弟总是在我不在家时看我的日记，真讨厌。