In pulsed power systems, the trigger generator is the component to generate electrical trigger pulses. Based on a pseudospark switch, a pulse transformer and a pre-ionized peaking switch, a 200 kV trigger generator with stable output, fast rise-time, and wide pulse width is designed and constructed. The operating theory of the trigger generator is described. The design and experiment of each main component are introduced. A pre-ionized peaking switch with novel working principle and structure is investigated. The experiment results of the trigger generator show that the amplitude of the output voltage is between 210 kV and 218 kV with a standard deviation of 1.8 kV. The rise time (from 10%–90% of the peak voltage) and the rise rate of the output trigger pulse are 17 ns and 11 kV/ns, respectively. The pulse width above 160 kV is about 300 ns.