HIV-1 Tat (1-86aa) coding sequence was inserted into the prokaryotic expression plasmid pET28a and transformed E. coli BL21(DE3). Tat protein expression was induced by IPTG and purified with Ni-NTA column affinity chromatography. Then， the TAR sequence was inserted into pBluescript II SK(+),which contain T7 promoter. The TAR RNA was synthesized by T7 RNA polymerase transcription in vitro. The binding activity of Tat with TAR was observed by capillary electrophoresis, positive compound AP064 was used to test the blocking effect on Tat-TAR binding. The results show that Tat can combine TAR effectively, and AP064 can block the binding. So the model can be used as screening compounds which can inhibit the binding of Tat and TAR.