Abstract: The current transformer with high quality PCB rogowski coils has big section structure which is opposite to the small section area requirement of the one with ideal rogowski coils.Through detailed theory analysis and formulas,the paper raveled out the limitation of big section and small section,and got conclusion that current transformer with big section and high quality PCB rogowski coils has the same measure principle as the one with ideal rogowski coils,which provides the theoretical basis for optimization design of current transformer with PCB rogowski coils and its application in the power system of mining area.The experimental research result showed that the current transformer with high quality PCB rogowski coils has good measurement accuracy,parameters consistency,excellent transient performance,and perfect resistant ability to electromagnetism,which suits for the development trend with further digitalization of power environment and power system in mining area.