Disclosed is a circuit for stabilizing a high tension voltage of a CRT and a method thereof. A feedback unit receives a cutoff voltage from the CRT. A compensating unit calculates a variation quantity of the cutoff voltage on the basis of the cutoff voltage from the feedback unit. The variation quantity of the cutoff voltage is compared with a high tension voltage compensation data stored in a storing unit according to the variation quantity of the cutoff voltage. Accordingly, the circuit for stabilizing the high tension voltage of the CRT and the method thereof can overcome inaccuracy of the high tension voltage compensation due to delay, and cut down the production cost by removing an ABL circuit and a high tension voltage compensating capacitor. Since the ABL circuit is not used, it is also possible to perform partial compensation according to an alternating current variation quantity.