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为寻求提高变压器油纸复合绝缘特性可能途径，开展了纳米改性变压器油-纸复合绝缘频率响应特性研究。利用电介质频率响应法，对比测试了添加纳米改性前后油纸复合绝缘不同微水含量、在不同温度条件下，10^-4～10^-6Hz范围频率响应；建立基于Cole-Cole函数的弛豫模型分析实验结果，并通过最小二乘法拟合得到弛豫模型参数；分析小同微水含量及温度条件下添加纳米粒子对弛豫参数的影响。结果表明：所建立的弛豫模型能较好地反映油纸复合绝缘频率响应特性，弛豫模型参数能反映油纸复合绝缘状态的变化规律；添加纳米粒子引入了新弛豫机制，在低频及高频段，降低了油纸复合绝缘的介质损耗，在0．1～100Hz频率范围内却增大了其介质损耗，且随着温度升高及微水含量增加，影响越显著。“,”The research on dielectric frequency response of oil-paper composite insulation modified by nanoparticles was carried out in order to seek possible way to improve insulation properties thereof. The dielectric frequency responses of oil-paper composite insulation at different temperatures and moisture contents were measured before and after nanoparticles were added within the frequency range about 10-4~106 Hz. The Cole-Cole relaxation models were established to analyze the results. And the parameters of the Cole-Cole relaxation models were obtained by least squares fitting. Then the influences of nanoparticles addition at different temperatures and moisture contents on the relaxation parameters were discussed. The results show that the established relaxation models can reflect well the dielectric frequency response of oil-paper composite insulation and the variation rules of insulation state can be indicated by the parameters of relaxation models. A new relaxation mechanism is introduced by adding nanoparticles, thus the dielectric loss of oil-paper composite insulation modified by nanoparticles is reduced within low and high frequency ranges, while the dielectric loss is increased within the frequency range of 0.1-100 Hz. And the influence is increased along with the increase of temperature and moisture content.