Abstract: Using RT-PCR, Nested PCR and Half-nested PCR, 3 substitutes of cDNA fragments were amplified from total RNA extracted from spleens of experimentally infected rabbits. After cloned in pMD18-T vector,　they were analyzed by sequencing. F1, F3 and F51 fragments in 5′ half cDNA or 3′ half cDNA were substituted by genetic engineering　recombination. The reconstructed 5′ half cDNA and 3′ half cDNA were then ligated to a new full length cDNA. The mutation sites were confirmed to be corrected by the method of sequencing. The reconstructed cDNA show infectivity by primary identifications. The study established a foundation for reverse genetic system of CSFV.