The coral, whose main composition is aragonite-type calcium carbonate, has been widely used as bone substitute in clinic. However, the study on calcium carbonate bioceramic has not been largely reported due to difficulty in sintering calcium carbonate which is liable to evidently decompose at low temperature. In this study, a novel calcium carbonate composite ceramic was fabricated by sintering fast at a low temperature. A degradable, biocompatible phosphate-based glass (PG) which grew liquid at a low temperature was added as sintering agent in the sintering process. The sintering schedule was explored by thermal analysis. The phase composition, microstructure, compressive strength, and biocompatibility of calcium carbonate composite ceramics were evaluated. The results revealed that the optimum holding time at the sintering temperature was 20min. The obtained calcium carbonate composite ceramics did not produce calcium oxide but new compounds according to phase analysis. The compressive strength of calcium carbonate composite ceramics correspondingly increased with growing addition of PG ranging from 10 to 50 wt%. The cell proliferation on the calcium carbonate composite ceramic was not compromised but augmented compared to the neat calcium carbonate ceramic without adding PG as sintering agent. The novel calcium carbonate composite ceramic is a promising bone substitute for bone defects.