The study was purposed to prepare the recombinant lentiviral vector pTK161 and pTK162 carrying B-domain-deleted canine factor (BDDcFVIII) gene, and to investigate whether the canine FVIII (cVIII) can be expressed in vitro. The BDDcFVIII gene was ligated behind PUB and 2OH1 promotors to create lentiviral vectors pTK161 and pTK162. Meantime lentiviral vectors pTK161' and pTK161' were produced by cloning a green fluorescent protein (GFP) into pTK151 and pTK152, which was driven by PUB and 2OH1 promotors respectively. Vector supernatant were prepared by using transfer calcium phosphate mediated-cotransfection of 293T cells. The virus vector, DeltaNRF packaging-plasmid, and VSV-G envelope-plasmid was assayed by titers and cFVIII activity in cell culture supernatant after infection into 293T cells. pTK161, pTK162, pTK161' and pTK161' were identified by restriction enzyme analyzing. The results showed that the lentiviral vectors pTK161, pTK162, pTK161' and pTK161' were successfully constructed, and the titers of pTK161' and pTK161' reached to 1.54 x 10(6) U/ml and 2.83 x 10(6) U/ml; the activity of cFVIII could be detected at 24 hours after infection of 293T cells by pTK161 and pTK162, and achieved the highest level at 72 hours later. The higher level of cFVIII activity was achieved by transfected with pTK162 than that of pTK161 (p < 0.05), which closed to the cFVIII activity in normal dog plasma. 1/4 of the highest level could be detected 6 weeks later. It is concluded that the prepared HIV1-based lentiviral vectors can infect 293T cells to express cFVIII effectively. The results provide the basis for further studying HIV-1-based lentiviral vector gene therapy for hemophilia A.