Thyristors have the advantages of good control characteristics, long life and low noise. At present, in the application of pulse power technology, the use of high-power thyristors instead of traditional gas switches is a research trend. Thyristors are used under high voltage, high current, and repetitive operating conditions, requiring careful selection and combination of switch components. Based on the failure mechanism of thyristors, the theoretical analysis, simulation calculation and experimental research on the heating of thyristor components under high voltage, high current, high di/dt, high du/dt and repetitive frequency are carried out. The use conditions of the thyristor components in repetitive frequency pulse power system thus have a theoretical basis. As the operating voltage, current, and frequency of the thyristor increase, the thermal loss of the thyristor increases and the heating of the thyristor becomes more serious. To ensure the safe and stable operation of the thyristor, the junction temperature needs to be kept within a safe range, and it cannot work at repetitive frequencies for a long time.