The invention relates to a diatomite-based cement board. The diatomite-based cement board is prepared from the following raw material components in parts by weight: 13-50 parts of diatomite, 35-0 parts of quartz sand, 32-42 parts of cement, 5-9 parts of wood pulp celluloses, 2-4 parts of mineral fibers, and 3-6 parts of inorganic filler. The invention also discloses a manufacturing method of the diatomite-based cement board. The diatomite-based cement board is produced by virtue of a traditional flowing slurry process, and the technology of the production process is quite mature; the diatomite-based cement board can be produced by virtue of the existing production line, so that the production cost is low. The diatomite-based cement board prepared from diatomite in stead of the traditional quartz sand as the siliceous raw material has excellent characteristics such as low weight, sound insulation, thermal insulation and high breaking strength.