Abstract: Currently most studies on metaphors in idioms are based on Conceptual Metaphor Theory (CMT), which is unable to interpret the emergent meaning adequately. However, the Emergent Metaphor Theory (EMT) can fill this gap and offer a new way for studies on idioms. This study based on EMT indicates that idioms cannot be analyzed entirely as syntactic constructions, nor can they be wholly understood as highly entrenched instances of metaphorical mappings. Highly figurative idioms cannot be understood within the bounds of the syntactic schema alone; their rich properties in meaning can be dug out only when both the syntactic schema and conceptual schema are taken into consideration. This provides a new perspective for the study on the cognitive mechanism of idioms.