GICs in technological conductor networks are a ground manifestation of space weather. During severe geomagnetic storms, if GICs flow in power systems, real and reactive power flow will swing abnormally, also transformer saturation, over-voltage fluctuation, frequency shift, unnecessary relay trippings and increased harmonic contents, even damage of transformer or a collapse of the whole system may occur. So GIC controlling in power systems is so significant that it can help power systems stand through strong geomagnetic disturbances, as well as ensure safe and stable operation of power systems. In this paper, control methods and techniques on GIC in power systems have been summarized in reference of research achievements and control experience on GIC.