The present invention relates to one kind of 2, 3, 2', 3'-tetrafluoro acetylene derivative and its composition, preparation process and use. The compound has the general expression as shown, relatively great optical anisotropy, relatively great negative dielectric anisotropy, relatively high light and heat stability and relatively low viscosity. The compound may constitute well behaved nematic phase liquid crystal composition with low threshold voltage, low viscosity, high response speed, improved response characteristic and contrast, and the nematic phase liquid crystal composition may be used in liquid crystal display of TN mode, STN mode, TFT mode, PDLC mode, etc. In addition, the compound has facile material and simple synthesis path, and the process is suitable for industrial production.