A high modulus glass fiber composition, and a glass fiber and a composite material thereof. The glass fiber composition comprises the following components expressed as percentage by weight: 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 crystallization 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 fiber having a low bubble rate.