The full-pouring busbar is adopted in 6 kV auxiliary power system in 330 MW units,which is applied at the first time in large power units of China.In order to guarantee the safe and reliable operation of the busbar,the methods of infrared thermograph,inter-segment contact resistance testing,insulation resistance testing and AC withstand voltage test are presented combining with the insulating structure of the full-pouring busbar.Furthermore,the dielectric power factor and capacitance are tested,and the BIM(betobar insulation mix)relative dielectric constant is estimated for further knowing the properties of the insulated materials.It is shown from the operation of the full-pouring busbar in recent years,that the on-line detection and off-line test are easy to implement,and the work load of maintenance and detection decrease substantially.