10 new rod-like azo benzoic acid liquid crystals belonged to three series have been prepared, in which trans-cyclohexyl benzene, biphenyl or bi-trans-cyclohexyl carboxylic acid mesogenic cores with ethyl, n-propyl, n-butyl or n-pentyl substituents were connected with azo benzoic acid. Meantime, a simple method was developed in synthesizing compounds bearing both ester and carboxyl groups in one-step reaction. All these compounds have been characterized on the basis of their spectral data, differential scanning calorimeter (DSC) and hot stage polarizing optical microscope (HS-POM). All these compounds have higher thermo-stability. 8 of these compounds have liquid crystalline properties. Their temperature ranges of mesophase have not been obtained, resulting from all the compounds decomposed before their clearing points. Although these compounds are photosensitive in solution under illumination of UV light (365nm), they can't do trans-cis isomerization in their mesophses, indicating the super stabilities of the trans isomer in mesophase.