你想知道对方的出生日期用英语怎么说

可以问 "What is your date of birth?" 来询问对方的出生日期。

例句：

Could you tell me your date of birth, please?
你可以告诉我你的生日吗？
May I have your date of birth on file?
我可以获得你的生日记录吗？

它的来源是英语表达中对生日的简称，用来替代"the day you were born"的说法。