High-entropy zirconate ceramics (HEZCs) have been studied extensively in recent years for the potential applications in thermal barrier coatings and high-level nuclear waste immobilization. While these HEZCs have the issue of poor toughness, which impedes their applications. The toughness of HEZCs can be improved by decreasing its grain size. While preparation of ultrafine-grained or nanocrystalline HEZCs is a challenge because the rapid grain growth inevitably occurred at high temperature densification process (typically above 1 500 ℃).In this work, the challenge of preparing dense ultrafine-grained high-entropy ceramics through conventional pressureless sintering process was addressed via a simple two-step sintering method. Ultrafine-grained (Ce0.2Nd0.2Sm0.2Gd0.2Y0.2)2Zr2O7 high-entropy zirconate with 99.0% theoretical density and 162 nm grain size was fabricated. Compared to the conventional method,two-step sintering provided the high-entropy zirconate with finer grain size and better microstructural uniformity, and excellent comprehensive mechanical properties including high hardness of 12.5 GPa and high fracture toughness of 2.4 MPa·m1/2. This workcould help to understand the sintering kinetics of HEZCs, and also supplied a guidance to prepare the ultrafine-grained or nanocrystalline HEZCs by pressureless sintering method.