Abstract: The infective clone of classical swine fever virus C strain was used as a skeleton. GP5 gene was used as a marker and was inserted into the infective cDNA clone. After in vitro transcription and transfection of SK6 cell, the recombinant sequence containing GP5 was detected. The results indicated that the GP5 gene was stably insert in the genome of CSFV. The recombinant virus of C strain can be possibly used as a marker vaccine.