Abstract: Filling epoxy resin with boron nitride (BN) nanosheets (BNNSs) can effectively improve the thermal conductivity of BN/EP nanocomposites, however, the severe agglomeration of BNNSs will significantly reduce the modification effects of the composites. In order to enhance the dispersion of BNNSs in epoxy resins, we adopted atmospheric pressure bipolar nanosecond pulse dielectric barrier discharge (DBD) Ar+H₂O low temperature plasma to hydroxylate BNNSs, then modified with silane coupling agent KH560. The elemental and hydroxyl content of BNNSs were investigated using X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), respectively, and the dispersion of BNNSs was quantitatively characterized using area distribution probability and impact properties. The test results show that the hydroxyl content on the surface of BNNSs increases by nearly two fold after plasma modification at 20% relative humidity, which enhances the adsorption of BNNSs on coupling agent. The coating amount of silane coupling agent on the BNNSs surface increases by 45% after plasma modification compared with BNNSs modified with coupling agent only. The dispersion characteristic value of BNNSs treated by plasma and silane coupling agent is increased by more than 10% than that of silane coupling agent treated only at the same mass fraction. This study provides a new method for enhancing the dispersibility of nanoparticles in composite materials.