Button-type metal diverter strips are commonly used for radome lightning protection, and their DC breakdown properties characterize their ionization performance in an environment adjacent to a lightning leader. In this paper, the DC breakdown voltage experiment of the diverter strip was carried out, and the ionization ability of different button-type diverter strips was analyzed. Results show that the increase of the length of the diverter strip result in larger breakdown voltages of the button-type metal diverter strip, but this increasing effect has a saturation trend. When the length of the diverter strip remains constant, an increase in the distance between the metal buttons corresponds to a higher breakdown voltage. Elliptical metal button-type diverter strips exhibit the lowest breakdown voltage, while rectangular button-type diverter strips display slightly weaker ionization capabilities compared to elliptical strips. Results here could provide a theoretical basis for the lightning protection design and optimization of button type metal diverter strips applied to radomes.