Abstract: The six compounds with high clearing points and low viscosity in the series of1-(4-alkylcyclohexy1)-2-4-(4-alkylcyclohexy1)pheny1 ethane were synthesized. Theirstructure were determined by means of IR,mass spectrum and element analysis. The mixedliquid crystals were prepared,and their physical properties were examined.It is sure that theabove compounds lower the viscosities of the mixed liquid crystals and raise their NI clearingpoints.