In this work, KTN-NH2/PI nanocomposites with high breakdown strength and low dielectric loss were obtained by modifying the KTa0.5Nb0.5O3 surface with 3-(2-aminoethylamino) propylmethyldimethoxysilane (APDS). Compared with KTN/PI, the loss tangent (tan delta) of KTN-NH2/PI was decreased. The breakdown strength (Eb) could reach to 242.12 kV/mm, which is about 1.49 times higher than that of KTN/PI. Based on the molecular dynamics simulation, the interaction between the modified KTN-NH2 and the PI matrix was higher than the KTN/ PI, which would reduce the tan delta by restraining the dipole orientation polarizations. Moreover, the increase of hydrogen bonds improve the interfacial compatibility, which reduce the electric field distortion of organicinorganic interface and improve Eb.