The invention relates to a high-voltage DC constant reactive power AC fault recovery method and device. The high-voltage DC constant reactive power AC fault recovery method comprises the steps of differencing the reactive power consumed by a converter and the reactive power provided by a reactive power compensation device of a converter station according to converter bus voltage and direct current to obtain an exchange reactive power allowance range of an AC system and the converter station, selecting an exchange reactive power expected value from the exchange reactive power allowance range, and generating a direct current instruction value; and performing AC fault recovery on the converter station based on the direct current instruction value. In the AC fault recovery process, the exchange reactive power of the AC system and the converter station can be quantitatively controlled at the expected value, thereby improving the fault recovery performance of the system, and reducing the probability of commutation failure during the AC fault recovery process; and the high-voltage DC constant reactive power AC fault recovery method improves the voltage stability of a multi-infeed direct current system and the fault recovery performance of the system, and has importance significance for improving the stability of a direct current transmission system.