Abstract: The surface modification of zirconium oxide （ZrO2） powders was performed through emulsion coating to improve their dispersion in the polypropylene （PP） matrix. The dielectric， thermal， and mechanical properties of the modified ZrO2/PP （PP/g-ZrO2） composites were investigated. The results indicated that the dielectric constant of the PP/g-ZrO2 composites increased to 4.28， and their dielectric loss increased from 0.007 1 to 0.068 at a frequency of 1 kH at a ZrO2 content of 50 wt%. In addition， the thermal stability of the PP/g-ZrO2 composites was significantly improved， and their tensile strength reached 38.33 MPa at a ZrO2 content of 20 wt%. Through analyzing the agglomeration state of ZrO2 in the PP matrix before and after modification， the composites achieved optimal overall performance at a ZrO2 content of 30 wt%.

Key words: zirconium oxide, polypropylene, dielectric property, thermal stability, composite