With the nature of objectively fixity and sociality, lexical affective meaning is affiliated to and changes with lexical meaning. From the perspective of socialinguistics, this paper firstly puts forward the concept of meaning infection, and concentrates on the two major paths of meaning infection in lexical affective meaning changes. Then, according to Greshams Law in economics, an analysis and prediction of those lexicons which have experienced meaning infection has been made towards their development tendency. It has been concluded from the research that they either tend to be taboo words, and even disappear from daily use; or become euphemisms to play a mild role in language communication.