Traditional cellulose paper is easy to accumulate space charge under the action of DC electric field

thus causing distortion of the electric field inside the medium. To improve the space charge characteristics of oil-impregnated cellulose insulation paper under DC electric field

and make the space charge difficult to accumulate and easy to dissipate

the cellulose insulation paper was modified with nano-Al

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. The space charge density of oil-impregnated modified paper samples with different nanometer contents under DC electric field was tested by pulse electroacoustic method（PEA）

and the characteristic parameters of trap were calculated. The results show that samples with 1% quality fraction nano-Al

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can improve the space char

ge behavior to the most degree. The doping of nano alumina can stimulate the formation of deep traps

which increases the density of deep traps and changes the trap energy distribution in cellulose insulation paper.The change of the trap characteristics explains the change of the DC breakdown field strength and volume resistivity of the insulating paper with the quality fraction various of nano-Al

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. The research results can provide references for further research on the modification technology of cellulose insulation paper and the improvement of various properties of cellulose insulation paper.