On-line Detection is very important for XLPE Power Cables running.The AC Superposition Method is efficient method for XLPE Power Cables’ water tree deterioration detection.Its key problem is the precision measuring of the weak 1 Hz characteristic current which is the token of water tree deterioration.In this paper

theory of controlling chaos is introduced in the XLPE Power Cables water tree on-line detection and a special chaotic system is put forward to precise measure the 1 Hz characteristic current

which based on that the Duffing chaos oscillation is respond sensitively to the ’same frequency’ periodic signal and immunity to the ’biggish frequency difference’ periodic signal with the periodic instigated force.The results of experiment show that the chaotic system can effectively to detect the 1 Hz characteristic current precisely and sensitively.