The meaning processing and mental representation of idioms are based on semantic compositionality.The semantic compositionality of idioms is generally analyzed with reference to the internal semantic structure of idioms, and there are different degrees of compositionality between the component meaning and the conventional meaning of idioms.Based on the Idiomatic-Activation Set Model, three major categories of idioms - regular compositionality idioms, irregular compositionality idioms and non-compositionality idioms will be introspectively analyzed. The complex correspondence between literal me...