Abstract: Cermet Composites ZrO₂(3Y)/WC-20% Co with different ZrO₂(3Y) contents were prepared by normal vacuum hot isostatic pressing. The mechanical properties of the composites such as hardness, bending strength and impact toughness were tested, and SEM was used to characterize the microstructures and components. The phase transformation contents of m-ZrO₂(3Y) to t-ZrO₂(3Y) before and after mechanical tests were measured by X-ray diffraction quantitative phase analysis. The experimental results show that the ZrO₂(3Y) particles are spherical particles with different sizes in WC-20% Co matrix and distribute uniformly in Co phases and WC phases. The bending strength and impact toughness of the cermet composites are improved remarkably, but little in hardness.