The design process and experimental results of a transfer capacitor used in a large vertical polarization bounded wave simulator are introduced. The capacitor adopts modular design based on capacitor elements and components, and forms a cone shape. The shell is made of vacuum process glass fiber reinforced plastic material. The capacitance value of capacitor is determined by the equivalent two-stage pulse compression circuit of the simulator, which is calculated to be 1.8 nF. The internal insulation medium of capacitor is dodecyl benzene, while the external insulation environment is 45# transformer oil. The designing working voltage is 3 MV, and the capacitor’s insulation length is mainly determined by the body insulation characteristics of capacitor elements. Three-dimensional electromagnetic simulation is used to estimate the inductance of the circuit composed of capacitor and switch, and the result is close to the measured data 623 nH. The measurement for the pulse voltage of capacitor is achieved by integrating the current of the capacitor, and the acquisition of the current is realized by a measurement module which consists of three oxidation film resistors in parallel and encapsulated in SF₆ gas. The actual operation data show that the designed capacity of the transfer capacitor is achieved and the calibration coefficient of the measuring device is stable and the working voltage can reach up to 3.1 MV.