As a novel non-destructive test method

frequency-domain dielectric spectroscopy（FDS） has been widely used for diagnosis and assessment of oil-paper insulation systems.However

the measurement of this method is influenced by some factors such as temperature and spacial electric filed

during on-site test

which leads to difficulty in accurate diagnosis of insulation.To improve the accuracy and reliability of oil-paper insulation diagnosis by FDS

some typical oil-paper insulation samples were prepared by the authors in laboratory based on the equivalent XY model of transformer.The influences of temperature

connection mode and insulation structure on FDS were investigated under controlled temperature and different sample status.Results show that each influencing factor has distinctive effect on FDS

and the effect can be eliminated by temperature correction and proper connection.