装饰圣诞树用英语可以说作 "decorate the Christmas tree."

这个短语来源于圣诞节传统习俗，即在圣诞节前夕在家中或公共场所摆放一棵装饰好的圣诞树，作为庆祝圣诞节的一种方式。

下面是一些例句：

It's time to decorate the Christmas tree!

Have you ever decorated a Christmas tree?

The children helped decorate the Christmas tree with ornaments and lights.

We always decorate the Christmas tree together as a family.