When on-site error verificaition is conducteded for 1000kV UHV current transformer in GIS, due to length test circuit and large impedance, conventional test methods have the problems of flow difficulty and operation complexity. Based on study of structure and feature of UHV current transformer in GIS and years of on-site operation experience, this paper designs and implements intelligent on-site error verificaition systemSfor 1000kV UHV current transformer in GIS.The composition and implementation scheme of the system is introduced. Power electronic power supply and electrical power supply series technology, adaptive reactive power compensation technology and intelligent verification technology are proposed, and the hardware and software design methods of the intelligent power frequency power are introduced. Verificaition experiments for 1000kV current transformer in UHV Nanjing and taizhou station show that the verificaition system can calculate accurately the electrical parameters of the tested current transformer, adjust automatically reactive power compensation, realize automatically resonance rising flow and error verificaition,and therefore improves the technical level of on-site test and the working efficiency.