The invention discloses an electrospinning technique-based ceramic diaphragm and a preparation method thereof. The preparation method comprises the steps of using a spinning nanofiber layer as a base membrane, and then coating/cast coating the base membrane with ceramic slurry or a ceramic precursor solution so as to obtain the final product. The ceramic diaphragm prepared by the method is high in porosity, thin in thickness and good in ion permeability; ceramic particles are introduced into the ceramic diaphragm, so that the thermal contraction of the ceramic diaphragm is greatly reduced, and the high temperature resistance of the ceramic diaphragm is improved.