Partial discharge（PD）occurs when the insulation of high voltage equipment degrades. The discharge signal is composed of electromagnetic waves with different wave lengths

which may radiate into the air outside the equipment. In this paper

rectangular UHF antenna array made up of four disk-cone antennas is used to receive the radiated UHF signals from air. Partial discharge source could be detected and located by moving detection of the array. Emphasis is laid on determining the initial time of each signal and the time difference of the arrive（TDOA）by making use of first peak of signal. Experiments verify the validity of the proposed direction location algorithm based on rectangular antenna array.