NOVELTY - Glass fiber produced by preventing crystallization in a cooling part, is claimed. Production of the glass fiber comprises (i) taking sodium oxide, aluminum oxide, silicon oxide, and calcium oxide, (ii) melting glass raw material and conveying into the cooling part, (iii) setting 2-40 temperature-measuring devices and 2-60 heating devices in the space above the level of glass liquid in the cooling part, (iv) starting the heating devices to heat and then stopping heating of the heating devices, and (v) stretching to form glass fibers, and cooling.    USE - The glass fiber is useful for e.g. glass fiber composite material aircraft shell structure, aircraft, and chemical petroleum pipe (all claimed).    ADVANTAGE - The glass fiber has increase strength. The method is energy saving and does not generate air bubble.    DETAILED DESCRIPTION - Glass fiber produced by preventing crystallization in a cooling part, is claimed. Production of the glass fiber comprises (i) taking 0.01-8 wt.% sodium oxide, 10-35 wt.% aluminum oxide, silicon oxide with content of 1.8-5.58 times that of calcium oxide, and calcium oxide with content of 0.8-2.1 times that of magnesium oxide, (ii) melting glass raw material and conveying into the cooling part, (iii) setting 2-40 temperature-measuring devices and 2-60 heating devices in the space above the level of glass liquid in the cooling part, at a distance of 10-80 mm from the inner side of a refractory brick wall of the pool, where the distance between the heating devices is 0.3-2 m, (iv) starting the heating devices to heat when the temperature at the cooling part measured by the temperature-measuring devices is less than 50 degrees C of crystallization temperature of the molten glass, and stopping heating of the heating devices when the temperature at the cooling part measured by the temperature-measuring devices is more than 100 degrees C of crystallization temperature of the molten glass, and (v) directing the molten glass from the cooling part to multiple holes in a high-temperature resistance porous metal plate, stretching at a high speed to form glass fibers, and cooling to obtain glass fiber product. INDEPENDENT CLAIMS are also included for:    (1) a glass fiber composite material, comprising a plastic substrate, and the glass fiber embedded in the plastic substrate;    (2) a glass fiber composite material wind blade, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (3) a glass fiber composite material wind blade shell, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (4) a glass fiber composite material wind blade root, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (5) a glass fiber composite material wind blade structure beam, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (6) a glass fiber composite material hull ship structure, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (7) a glass fiber composite material aircraft shell structure, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material;    (8) a wind power generation device, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material to form phoenix power blade, shaft, electric generator, and wind power tower;    (9) a water ship, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material to form ship structure, power plant, cockpit, and boat;    (10) an aircraft, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material to form power device and control system device; and    (11) a chemical petroleum pipe, comprising a plastic substrate, and the glass fiber embedded in the glass fiber composite material.