Some novel trigonal Schiff base compounds with aromatic core and different substituted groups have been designed and synthesized from the reaction of trigonal aromatic amine with different aldehydes. It has been found that depending on the molecular structures and substituted groups, the formed trigonal Schiff base compounds showed different properties, indicating distinct regulation of molecular design. UV and IR data confirmed commonly the formation of Schiff base as well as aromatic segment in molecular structures. Thermal analysis also clarified the structural influence of these compounds in different temperature ranges. The difference of thermal stability is mainly attributed to molecular structures, formation of Schiff base group and different substituted groups. The present results have showed that the special properties of Schiff base compounds could be turned by modifying molecular structures and substituted groups, which show potential application in fields of functional material and catalyst.