Abstract: The research on Monad is now mainly focusing on functional programming languages,and is mainly about problems on its internal form and features. Yet referring to the relation of Monad to practical programming languages, there is little mention of how to construct programs with Monad and how to apply Monad in software formalization. This paper is concerned with the relation between Monad technique and OO technique, with emphasis on the relation between Monad and Class. And furthermore, one way to transforming Monad into Class （C + + ） ispresented.