The structure X dehen(得很)in Shaoyang dialect has many kinds of usage.Except expressing high degree,it can express the urgency,necessity or probability of an action or an event. In Shaoyang dialect, dehen(得很)lexicalizes from a cross-layer structure to a modal word,and in the course of its evolution, it gets the modal function.Its’ evolution route accords with the grammaticalization patterns of ‘Dynamic Modal>deontic modality>epistemic modality’ by and large,which is a common grammaticalization patterns of human languages.