Abstract: Polyimide/nano-TiO2（PI/TiO2） hybrid films were fabricated via in-situ dispersive polymerization and corona-resistance of films was studied.The trap state and ultraviolet absorption spectra of the films were measured by photon-stimulated discharge（PSD） and ultraviolet spectrophotometer.The surface morphology and fractal characteristics of the films were also analyzed by SEM and small angle X-ray scattering（SAXS）.The results show that the trap density and mass fractal dimensions of hybrid films increase as TiO2 is filled into PI.Meanwhile,surface fractal appears at 5% doping.The variation of fractal characteristics proves hybrid films with more compact and complex structure.With the TiO2 doping concentration increasing,the time-tobreakdown of the hybrid films can be lengthened from 3.9h（0%） to 49h（7%）,and ultraviolet absorptive capacity is improved.With the corona ageing continuing,PI matrix on the surface of films decomposes.Then,a large number of TiO2 particles are gradually accumulated and play a role in shielding further erosion.The corona-resistance of hybrid films is enhanced by synergistic effects which are composed of trap state in the interface,TiO2particles properties and film fractal characteristics.