A series of liquid crystalline binary polymer blends consisting of P1 with a dimethylamino group as an electron donor and P2 with a nitro group as an electron acceptor was prepared and investigated by using DSC, optical polarized microscopy and x-ray diffraction. The binary mixtures of their model compounds 4-hexyloxy-4'-nitro-azobenzene (MA) and 4-hexyloxybenzylidene-4'-(N,N-dimethylamino)-aniline (MD) were also prepared and investigated. The results show that these binary mixtures have good miscibility and exhibit broader mesophase ranges than that of the individual acceptor and donor, which are considered to be caused by the interactions between the electron donor and acceptor groups. For example, the isotropic temperature of the 1:1 polymer blends is 441.5K, which is 48K higher than the calculated value based on the composition without any interaction, while its melting point is 28K lower than the calculated value. And for the 1:1 mixture of MA and MD, the isotropic temperature was 20 degrees C higher than the calculated value and the melting point was 19 degrees C lower than the calculated value.