The invention discloses a portable small current earth-fault line selection closed loop performance tester. The portable small current earth-fault line selection closed loop performance tester is composed of a man-computer interface, a master control module, a waveform database, a signal output module, a communication module and the like. According to the portable small current earth-fault line selection closed loop performance tester, due to the fact that a typical offline power distribution network model is established, the single-phase earth fault scenes of a small current grounding system in various modes are simulated accurately, current and voltage waveform data reflecting the fault characteristics are led into the small current earth-fault line selection tester, a line selection result for a device to be tested is obtained automatically according to the output of the device to be tested by connecting the tester with a communication interface of the device to be tested, then an automatic closed loop testing system is formed, in this way, the actual line selection accuracy and the rationality of line selection strategies and parameter setting are checked, the operating efficiency and the maintaining efficiency of the device are improved, on-site transient state performance testing of the small current earth-fault line selection device is achieved, an effective method is provided for inspection, acceptance and regular maintenance of the small current earth-fault line selection device, and the device plays an important role and has great significance in improving small current earth-fault line selection accuracy.