Effective detection of partial discharge（PD）in ultra high voltage（UHV）transformer is very important to ensure safe and reliable operation of UHV power transmission system. Propagation of PD signal in transformer wind-ings causes signal attenuation and distortion

which makes accurate fault diagnosis of transformer difficult. In this pa-per

a finite element model of one-pole transformer winding is established based on the theory of multi-conductortransmission line（MTL）and the single-phase 5-pole structure features of a UHV transformer to study the propagationcharacteristics of PD signals. The distribution parameters of resistance

capacitance and inductance of the windingsare calculated. By solving the MTL equation

the response of each turn in the winding is obtained while PD occurs atthe outlet of the UHV transformer. The propagation characteristics of PD are analyzed. Results show that: 1)the PDsignal propagates in the winding at a certain speed;2)the voltage has low-frequency oscillation with a long duration;and 3)the current attenuates significantly along the winding and flows mainly into the ground through the capacitance between the winding and the core or transformer case.