The invention discloses an erosion-resistant acid-resistant crack-resistant zero-expansion silicon brick and a preparation method thereof. The preparation method comprises the following steps of: S1,selecting raw materials: selecting 80-90% of fused quartz, 10-20% of silicon powder, 0.1-3% of carboxymethyl cellulose and 1-5% of silica sol; S2, mixing raw materials, namely mixing the selected rawmaterials, adding SiO2, Al2O3, Fe2O3 and CaO into a stirrer to stir and mix after mixing, and obtaining a mixture after trapping materials; S3, pressing and forming: putting the mixture into a press machine, and pressing and forming by one-way pressure to prepare a cylindrical sample; S4, drying: naturally drying the prepared cylindrical sample at room temperature, placing the cylindrical sample in a drying box to heat, and drying to obtain a dried sample; S5, sintering, namely putting the dried sample into a calcining furnace to heat, preserving heat and calcining to obtain a thermal shock resistant silicon brick. Compared with other preparation methods, the method has the advantages of low technical cost, mature process, easy realization and strong practicability, and greatly improves the using quality of the silicon brick.