The utility model relates to a high-potential electronic plate of a thyristor valve, which comprises a power supply module, a power supply state detection module, a valve end voltage detection and zero passing synchronous module, a power triggering module, a photo electric conversion module and a logic processing module. Compared with the prior art, the electronic plate of the thyristor valve has the advantages that the power supply energy taking mode is upgraded into high-frequency energy conveying from the voltage energy taking, the reliable energy taking can be ensured regardless of the operation conditions of a valve body, and the utility model is applicable to a high-voltage thyristor switching capacitor device. A two-way optical coupler is adopted for isolating the valve end high-voltage part and the electronic plate low-voltage part, a valve voltage detection module is designed again, the electronic plate of the thyristor valve can reliably detect on the valve voltage regardless of the positive pressure state and the negative pressure state of the valve body, in the control logic aspect, the return of zero passing synchronous valve end voltage is used as the criterion for the thyristor switching capacitor device to control the first investment moment of the capacitor, simultaneously, in order to improve the triggering reliability, the heavy triggering function is added through judging the valve end voltage.