According to the research through corpus, it is easy to find that `hui` does not always show the basic meaning of ability or possibility. This paper tried to find what kind of function does `hui` has in the pluractionality sentences.
If there is any ingredient can give pluractionality reading to the sentence, `hui` would be used to show the tendency of the subject. Normally `hui` can be omitted, but there will be some difference of the meaning. As `hui` is the marker of irrealis from the joint system view, other ingredient shows that the event or state is iternative and `hui` has the function of expressing that the conclusion is got from the speaker`s judgement. If the speaker wants to send the message objectively or emphasize the reality of it, `hui` can not be used. On the contrary, if there is some need to give prominence to the subjective characteristic of the sentence, `hui` must be used.