[en] The objective of this research is to develop the 0.3 ∼ 0.5 mm sized UO₂ microspheres for the kernel of the nuclear fuel. In this research, ZrO₂ microspheres were studied in stead of UO₂. The research was done with the detailed contents as follows, the development of well dispersed high solid loading ZrO₂ slurry : by the control of dipersion and the thixotropic properties of the slurry, high solid loading slurry with more than 60 wt% solid content could be made. And the slurry was turned to the formed microspheres by the liquid drop method. The dipersant and PH conditions were critical for the preparation of the slurry. Development of the microsphere fabrication and sintering process for the microspheres : by the liquid drop method with high voltage electricity, microspheres were successfully formed. and the sphericity of the microsphere were improved with the control of the slurry condition and forming process. The viscosity and binder content were controlled to make various sized microspheres