The synthetic calcium carbonate, as the application of papermaking filler, belongs to the papermaking technical field. The plant pulp fiber material is as the skeleton, synthetic calcium silicate power is as the filler, and the high paper filler is produced by paper-making technics. The synthetic calcium silicate power is as the hydrated calcium aluminate, and the object composition includes C-S-H polymer gel and tobermorite, and the brightness of synthetic calcium silicate power is greater than or equal to 90%, the specific surface area is greater or equal to 120 square meters per gram, the bulk density is from 0.12 grams per centimeter to 0.30 grams per centimeter, the oil-absorbed value is 120-200 milliliters per milligram, and the average grain diameter is (D50) from 12 microns to 40 microns . Meanwhile, the invention also discloses the preparation method of synthetic calcium carbonate: the synthetic calcium silicate power is the paper filler, then under the premise that paper properties are guaranteed, the usage of plant fiber can be decreased at the greatest extent. Replacing the traditional paper filler by synthetic calcium silicate power can not only reduce the usage of plant filler at the greatest extent, but also increase the retention rate of calcium carbonate, decrease the waste of filler and improve the paper ash content.