Every language have some modal expression what express the possibility and necessity, for example there are modal verbs and modal adverbs in English, and modal verbs, modal adverbs and possible complement for Mandarin Chinese. However in Mandarin Chinese, some modal expressions have similar semantic functions, as ¡§¯à(neng)¡¨, ¡§·|(hui)¡¨, ¡§¥i¥H(keyi)¡¨and possible complement, it could cause confusions to the learners. Furthermore, all of these modal expressions could translated as ¡§할 수 있다¡]hal su itda¡^¡¨ in Korean, so Korean learner would feel that is very difficult. Therefore, this study will contrast the modal expressions of Mandarin Chinese and Korean, and contrast novel¡m¶É«°¤§ÅÊ(Love of the beautiful women)¡nin Mandarin Chinese and Korean, try to explain the problems what the Korean learners could have when they acquire the modal expressions in Mandarin Chinese. Palmer¡]1986¡^classify the modality as epistemic modality, deontic modality and dynamic modality. And he classify the deontic modality as permission, obligation and promise, classify the dynamic modality as volition and ability. Hofmann(1993) classify the dynamic modality as ability and capability, and Porter(2009) classify as ability and opportunity. Present paper would accept the classification of Palmer mainly and refer to the classification of Hofmann and Portner, classify the modality as epistemic modality, deontic modality and dynamic modality, the deontic modality include obligation and permission, and the dynamic modality include volition, ability, capability and opportunity. The result of the study, the counterparts of modal expressions in Mandarin Chinese and Korean is very complicated. The ¡§¯à(neng)¡¨, ¡§·|(hui)¡¨, ¡§¥i¥H(keyi)¡¨and possible complement are equivalent to ¡§¡]으¡^ㄹ 수 있다¡]eul su itda¡^¡¨ altogether, but only negation of ¡§¯à(neng)¡¨, ¡§¥i¥H(keyi)¡¨and possible complement are equivalent to the negation of ¡§¡]으¡^ㄹ 수 있다¡]eul su itda¡^¡¨ , it will cause the difficulty of Korean learners.