The invention relates to the field of charging monitoring of nuclear power stations, and discloses a charging monitoring system for a nuclear power station and a charging monitoring method for the nuclear power station. The charging monitoring system for the nuclear power station comprises a charger controller which is used for locking a charging parameter as a preset fixed value, wherein a direct-current monitor is used for automatically acquiring the preset fixed value of a charger device and adjusting the charging parameter in a fine tuning range. The charging monitoring method for the nuclear power station disclosed by the invention comprises the following steps: S1, adjusting the charging parameter of the charger device through the charger controller, and locking the charging parameter as a preset fixed value; S2, automatically acquiring the preset fixed value of the charger device through the direct-current monitor, and finely tuning the preset fixed value within the fine tuning range, wherein the fine tuning range is calculated according to the practical output differential value of each charger in the charger device. According to the charging monitoring system, the charging controller is arranged, the charging parameter is adjusted to a fixed-value charging parameter, and the direct-current monitor can only be used for finely tuning the charging parameter, so that charging becomes safe, reliable and stable.