_{:In this paper, we find a broth formulation that is stable at room temperature for 15h and does not solidify and it is good for forming gel microspheres. And we use a capillary microfluidic device assisted internal gel process to prepare successfully small size (<120μm) ZrO2 ceramic microspheres. The factors affecting the size of ZrO2 microspheres are analyzed. The results show that under the same conditions, the larger the flow rate or the viscosity of the silicone oil, the smaller the size of the ZrO2 microspheres. The larger the flow rate of the broth or the larger the throat size of the capillary microfluidic device, the larger the size of the ZrO2 microspheres; the CV value of the ZrO2 microspheres are less than 5% by image recognition, indicating that the ZrO2 ceramic microspheres prepared by the method are uniform in size and monodisperse; the sintered microspheres are dense and showing a cubic phase by SEM and XRD.}