The invention provides a method of preparing a low-expansion heat-resistant ceramic plate. The method comprises the following steps: mixing raw materials of the plate according to a formula, performing ball milling by using a ball mill, after iron is removed, adjusting a water content of slurry, performing spray granulation, performing aging in a material bin, and preparing a blank by using an automatic brick machine to obtain a plate blank body; sending the plate blank body to a roller kiln, performing pre-sintering, performing pulverization, performing ball milling by using a ball mill, after iron is removed, adjusting a water content of slurry, performing spray granulation, performing aging in a material bin, and preparing a blank by using an automatic brick machine to obtain a plate; mixing glaze materials according to a formula, performing ball milling by using a ball mill, after iron is removed, adjusting a water content of glaze slurry, and coating the plate for 2-4 times; and sending the glaze-coated plate into a roller kiln, performing temperature programming for firing, and performing polishing to obtain the finished product. According to the method for preparing the low-expansion heat-resistant ceramic plate provided by the invention, the product prepared by the method has the advantages of good heat resistance, high strength, a low expansion coefficient, and no water penetration.