Provided is a liquid crystal compound represented by formula I, the compound having a positive dielectric anisotropy, a great elastic constant and a good solubility. Further provided is a liquid crystal composition comprising the liquid crystal compound represented by formula I, the liquid crystal composition having a good stability against light and heat, a lower viscosity, a wider refractive index that may be achieved by the adjustment of the monomer ratio, and a higher clearing point (a very wide service temperature range), and in particular, the liquid crystal composition has a higher light transmittance, thus allowing a display device to have a higher brightness or an energy saving effect.