Abstract: An experiment in view of repetitive frequency electromagnetic pulse (EMP) interference, take the hydrogen thyratron trigger as research object, is carried out to study the interference of the hydrogen thyratron first grid and second grid under the condition of suspension and mutual ground. The results show that the two grids have intense electromagnetic interference (EMI), and the interference is mainly caused by space electromagnetic radiation and coupling of mutual ground. The experiments are separately carried out under the EMP environment with different repetitive frequency quantity and time interval. The results show that the two cases have impact on tube trigger, increasing repetitive frequency EMP quantity and reducing EMP interval both increase the probabilities of false trigger. Comparing with the theoretical analysis and the experiment results, it is concluded that this phenomenon is caused by repetitive frequency accumulation effect and high frequency component strengthen which leads to enhanced coupling.