Provided are a high modulus glass fibre composition, and a glass fibre and a composite material thereof. The content, given in weight percentage, of each component of the glass fibre composition is as follows: 53-68% of SiO2, 13-24.5% of Al2O3, 0.1-8% of Y2O3 + La2O3, less than 1.8% of La2O3, 10-23% of CaO + MgO + SrO, less than 2% of Li2O + Na2O + K2O, and less than 1.5% of Fe2O3, and the range of a weight percentage ratio C1 is more than 0.5, wherein C1 = Y2O3 / (Y2O3 + La2O3). The composition significantly increases the elastic modulus of glass, significantly reduces the liquidus temperature and the forming temperature of glass, and under equal conditions, significantly reduces the crystallisation rate and the bubble rate of glass. The composition effectively improves the material properties of glass, and is particularly suitable for the tank furnace production of a high modulus glass fibre having a low bubble rate.