In this peper,a circuit theory model for the discharge circuit of "ShenGuang"FaCility,the caculated results for pontentials which are obtained on the basis of the theorymodel,a special pontential measuring circuit and the measured results are reported.Thecaculated results are in good agreement with the measured ones. All reported in this paperare very important,especially,the circuit model and the special measuring circuit are theprincipal means to improve the discharge circuit structure and to analyse and resolve the electromagnetic interference in “Shen Guang” Facility.