Abstract: After the reaction between 4'-alkyloxy-4-azo benzenal-dehydes and 4-substituted anilines, a series of unsymmetrically structured liquid crystals with para azobenzenaldimine residual(-N=N-???19900310???-CH=N-) as the central group is obtained. Theseries of liquid crystals has a rather higher and broader temperature region of mesophase because of their higher length-width ratio and the definite polarity.