The surge protective device (SPD), as buildings over-voltage protective device, has been widely used in building’s power distribution system. A novel SPD based on hollow cathode effects is designed. In both air and nitrogen gas, the relationship of discharging voltage and gas pressure are measured, and the critical pressure ranges are determined in the condition of UpUp is pulse voltage protection level). The results indicate that, in the condition of the gap distance D=3 mm and the small hole diameter φ=3 mm, the operating gas pressure ranges are from 50 to 5×104 Pa. With the gap distance D increasing, the pulse voltage protection level Up is decreasing slightly. While D=3 mm, φ=3 mm, and gas pressure (nitrogen) is 600 Pa, the DC voltage protection level and pulse protection level are 784 V and 2.4 kV, respectively. In the action of 10/350 µs pulse current waveform, the quantity of transferred charge Q is 48.26 C, and the ratio energy W/R is up to 2 MJ/Ω. The results testify that the design of SPD in this paper can be used as buildings class B over-voltage protection.