Brain-derived neurotrophic factor is one of the most major neurotrophic factors in brain, there are a variety of biological functions such as nerve protection, restoration and prompting neurons,and so on. Due to the less content in brain tissue and exogenous BDNF can not through the blood brain barrier,its applications are limited. In order to research the feasibility of expression vector carrying BDNF through the blood-brain barrier, this study firstly built a targeted expression vector pGPAF – BDNF. from the NCBI ,we got the gene sequence of rat BDNF.with codon optimization, artificially synthesized rat BDNF full genetic sequence. after recovery, purification, enzyme digestion and reforming,it is connected to the pCMV carrier and the pcDNA pGPAF carrier, the recombinant plasmid pCMV – BDNF and pGPAF – BDNF transform into E.coli DH5a, screening positive clones and enzyme identification. the results show that we successfully clone the BDNF gene and build a targeted expression vector pGPAF – BDNF.