Lightning current online monitoring is of great significance for the stable operation of power system. Rogowski coil and differential ring are important sensors for obtaining full waveform of lightning current. This paper introduces the measuring principles of Rogowski coil and differential loop, as well as their development status domestic and overseas and their advantages or disadvantages. The possible future research directions are also discussed. Finally, this paper raises the power supply problem of on-line monitoring system for lightning current, and puts forward a feasible solution.