The utility model discloses a cathode-ray tube high-voltage step-up transformer, which is a step-up transformer, exporting quadruple voltage, which is formed by that based on a voltage-doubler rectifying circuit, two diodes are connected in series to be in the bridge connection between the earth and one end of the secondary high-voltage winding of a line output transformer, and a capacitor is connected between the contact point of the two diodes and the other end of the secondary high-voltage winding. Due to the high step-up ration of the utility model, the number of coils of the secondary high-voltage winding of the line output transformer is reduced dramatically under the condition that the value of anode high voltage is ensured, avoiding the high-voltage flash-over short circuit of the transformers. The utility model has the advantages of high reliability and low cost.