The invention provides a method for preparing a circuit board, comprising the following steps: a, selecting a certain quality slurry, and heating the slurry in a water bath at a water temperature of 85 DEG C; Selecting a substrate, and printing the substrate with the slurry in step a; (c) put that aluminum oxide substrate printed with the first lay of slurry in the step (b) into an oven at 130 DEGC for baking; and (d) baking the aluminum oxide substrate in the first layer of slurry at 130 DEG C for bake; and (d) baking the aluminum oxide substrate at 130 DEG C for baking for 1-2h; D, repeating two steps b and c of the substrate dried in the step c, and printing three layers; Placing the printed substrate in the step (d) into a high-temperature electric furnace, raising the temperature from room temperature to 1000 DEG C at a rate of 2 DEG C/min, keeping the temperature at 1000 DEG C for 2h, and naturally cooling; F, adopting high-temperature silver paste, firstly printing four layerson the circuit substrate prepared in the step e according to the steps c and d, then placing the four layers into a high-temperature electric furnace, increasing the temperature from room temperatureto 830 DEG C every 2 DEG C/min, keeping the temperature at a constant temperature of 830 DEG C for 2 hours, and then naturally cooling the circuit substrate. The preparation method improves the product quality.