Based on terms borrowed from Catford's theory,this paper is to redefine Jakobson's concept of intersemiotic translation by dividing it into two subtle types called intersemiotic transference and intersemiotic shift respectively.The former requires the properties of signs to remain unchanged during the translation process and emphasizes transference among different sensory signs or null symbols,which extends the scope of translation studies in a broad sense;the latter pays attention to the change of sign properties during translation activities and can be further classified into three stages which influence the selection of ST,deconstruct the ST and generate the way in which TT is produced.The case study of Yan Fu's translation has proved the rationality of such classification while proving us with a new perspective to investigate Yan Fu and his translations.