When I think about it, it makes my mouth water.
想起它我都会流口水。
固定表达make one's mouth water,就相当于汉语中的“使……流口水”,是个不太正式、偏于口语的用法。
例句:
The roast duck that restaurant serves is my favorite dish. Every time I think about it, it makes my mouth water.
我最喜欢吃那个饭馆的烤鸭。每当我想起它我就会流口水。