Abstract: The spacecraft of operating in the sunlight will be affected by photoelectrons，and positive spacecraft potentials is up to several tens of volts at the illuminating surface of spacecraft.The charging phenomenon of spacecraft seriously impact on the safety and stable operation and accuracy of detection of its data.The velocity and spatial distributions of the ions and electrons are distorted in the electric field around the positive charged spacecraft，and plasma electrons are accelerated in the sheath.In addition，the reattracted photoelectrons enter into the sensors and cause high count rates at low energies，which not only makes it extraordinarily difficult to detect features of the low-density plasma but also accelerates the aging of the microchannel plates used in the instruments.Liquid metal ion source of active spacecraft potential control has been widely used in many satellites，which is introduced in this paper.China has to independently develop this active potential controller meeting the needs of space exploration，and providing protection and security for reliable operation in orbit to our military and application satellite.