The purpose of this paper is to analyze the streaming electrification mechanism (SEM) generated in UHV transformer. This experiment used Couette Charger and interpreted the mechanism hydromechanically and electromagnetically. This work estimated the turbulent core density ($ ho$o) by measuring the short circuit current (isc) and the open circuit voltage (νoc) generated in Couette Charger and also studied the changes of the short circuit (isc), the open circuit voltage (νoc), the turbulent core density ($ ho$o) and the conductivity ($sigma$) with adding BTA to restrain streaming electrification. as a result adding BTA increased the conductivity of oil and decreased the turbulent core density($ ho$o).