Abstract: In theoretical studies of contrastive linguistics(CL),the controversy on the issue whether similarity or difference is the purpose of contrastive analysis has,to some degree,affected the development of CL proper.An effective solution,besides the continuing endeavor for an ideal contrastive model,is to demarcate the terms of contrast/compare,commonness/individuality,diachronicity/synchronicity,etc.and to redefine CL from the perspective of the nature and objectives of the discipline.