In the past decades, many XYZ states have been observed by experiments. Some of them cannot be accommodated in the conventional quark model as QQ\bar and thus become excellent candidates for exotic states. Since the masses are close to the threshold of a pair of charmed mesons, so some of them may be good candidates of the hadronic molecule. The charmless decay processes of exotic states provide us a good platform to study the nature and the decay mechanism of exotic states. In this talk, based on the hadronic molecule assumptions, we will discuss the charmless decays modes of X(3872), Zc(3900).