The invention discloses a railway bar-shaped porcelain insulator used for a high-speed railway, which comprises a porcelain insulator body and a metal flange body that forms a whole body together with the porcelain insulator body, wherein the porcelain insulator body is prepared by adopting the following steps: adopting high-aluminum bauxite, feldspar, mullite and clay as raw materials, adding into a ball mill, evenly mixing to form slurry, filtering and removing iron, spraying and drying to prepare powders, pressing the powders to form a blank under the isostatic pressure, cutting and processing, sandblasting and glazing, sanding on the cementing surface at two ends, carrying out drying treatment, firing at the maximum temperature below 1250 DEG C, carrying out appearance and ultrasonic flaw detection, and sealing and cementing by cement glue between the flange body and the cementing surface at two ends to form the whole bar-shaped porcelain insulator. The bar-shaped insulator has the advantages of fine crystal grains, large density, high strength and small dispersity; the bending load withstand strength of the bar-shaped insulator can reach more than 24KN/cm<2>, and the torque load reaches more than 10KN.m and can completely satisfy the technical requirements of porcelain insulators used in a high-voltage power transmission grid of the high-speed railway.