The obsolete word“appliable”has been revitalized by M.A.K.Halliday in his call for“appliable linguistics”in the twenty-first century.This paper argues for the fact that the thematic notion“appliability”and its accompanying principles for linguistic research also hold true for our development of semiotic theories.As we all know,signs and symbols play a very important role in our daily communication;thus it will argue that a powerful semiotic theory should be closely related to practice and proved workable and effective in practice.It follows that the study of meaning should be the chief concern of semiotic theories,and that a dynamic view toward the relation between signifier and signified is needed.The paper will argue that we should learn to pinpoint the choice of the expected meaning according to social accountability,that is,the culture,the topic,the participants,the circumstance,etc.,and that because of the development of science and technology,we should also see the importance of multimodality in communication.Finally,it will conclude that an appliable semiotic theory should learn how to improve and revise itself constantly in order to meet new challenges.