The invention discloses a preparation method of a ceramic-based electronic substrate material, and belongs to the technical field of the preparation of ceramic substrate materials. The method comprises the following steps: mixing and ultrasonically dispersing yttrium nitrate and calcium nitrate, drying to constant weight, sintering and nitriding to prepare nanometer aluminum nitride, mixing with dehydrated and milled samarium nitrate, carrying out ball milling, drying to constant weight, grinding, screening and then calcining, mixing with the paraffin, extruding and pelleting, drily pressing to prepare a blank body, degumming, and sintering to obtain the ceramic-based electronic substrate material. The method disclosed by the invention has the beneficial effects that the preparation step is simple, the obtained product is good in sintering performance, the pore is avoided in the sintering, the material flexure strength is high; the surface compactness is good, and the phenomena of moisture absorption and electrode slurry penetration are avoided.