The utility model relates to a small current grounding line selection tester. The small current grounding line selection tester comprises a main control module, a PCI bus and control module, a man-machine interface module, a waveform database management and control module, a simulation signal output control module, an input/output signal control module and a communication control module. A hardware framework of the small current grounding line selection tester is based on a PCI bus, the small current grounding line selection tester has excellent expansibility and compatibility, a typical power distribution network model is established, single phase grounding fault scenes of a small current grounding system in various modes are accurately simulated, current voltage waveform data reflecting fault characteristics are guided to the small current grounding line selection tester, through connection with an output amount and communication interface of to-be-detected equipment, the line selection result of the to-be-detected equipment is automatically discriminated, and an automatic closed loop test system is formed. The small current grounding line selection tester provides effective means for acceptance and regular maintenance and has great importance and meaning for small current grounding line selection accuracy.