This paper has synthesized four isothiocyanato-diphenyl acetylene liquid crystal compounds. Their structures were identified by IR,1 HNMR,13 CNMR,19 FNMR, MS spectra. Their phase transition temperatures were tested by using differential scanning calorimetric (DSC) and polarizing optical microscopy (POM). It is found that all of the new compounds show nematic phase, and their phase transformation temperature was in the range of 105°C to 137°C. Their birefringence are more than 0. 47, which can be used as the effective components of high birefr...