Abstract: Avalanche gallium arsenide photoconductive semiconductor switches (GaAs PCSSs ) have a wide range of applications due to their ultra-fast switching speed, low triggering jitter , optoelectronic isolation , high power capacity, high repetition frequency, and flexible device structure. In this paper, GaAs PCSSs with an anisotropic structure and an electrode gap of 5 mm are fabricated and packaged. The electrical characteristics of the switch in dark-state and on-states under different bias electric fields (36−76 kV/cm) are analyzed, featuring a rising edge in the order of hundred picosecond to nanosecond, low dark-state leakage current (0.15−6.61 μA) and high withstand voltage (18−38 kV). The relationship between the number of switching operations and the peak output voltage is explored. The experimental results show that the output voltage amplitude tends to decrease in a stepwise manner with the increase of the number of operations. The switch lifetime reaches 4.0 × 10⁴ times at 20 kV and 2 Hz.