The invention discloses a preparation method of a SiALON and silicon carbide combined ceramic. The preparation method comprises the step of dosing, ball-milling, mixing, ageing a slurry, processing aplaster mold through slip casting, and drying a biscuit and sintering at the high temperature; in the dosing step, the basic material comprises the following ingredients by weight: 30-41.5 wt% of a coarse silicon carbide particle with the particle size of 60-150 mum, 30-41.5 wt% of a fine silicon carbide particle with the particle size of 1-50 mum, 15-30 wt% of silicon metal, 2-5 wt% of aluminum oxide, 0-1 wt% of ferric oxide, and 0-1.6 wt% of rare earth oxide. The preparation method adopts the slip casting process, the technological process of production is simplified, the production cost islowered, a prepared product is high in high-temperature inoxidizability, high in mechanical strength, and good in thermal shock resistance, and is wear-resistant and corrosion-resistant.