Abstract: The nucleation and crystal growth of calcium bilirubinate crystalls in four different aqueous biomi-metic systems were studied by FT-IR, XRD, SEM and TGA, and the effect of biomacromolecules and CO₂ on the crystal nucleation of the calcium bilirubinate was investigated. The results indicated that the calcium bilirubinate crystals couldn't form spontaneously in the aqueous solution, while multiple crystals of calcium bilirubinate and calcium calcite coexisted and the mass content of the calcium calcite was about 12%. In the course of the nucleation and growth of the multiple crystals, crystal calcium bilirubinate with two obvious X-diffraction peaks at 2θ 19.8° and 21.8° were induced by the dextran and the calcite crystal formed under the effect of CO₂ in the air. In the process, proper sites for the nucleation of calcium bilirubinate were provided by the crystal surface of the calcium calcite and the oxygenous function of the dextran molecules due to the effect on the coordination between the Ca²⁺ ions and the bilirubin, and the growth of the crystal calcium bilirubinate with a distinct decomposition temperature was induced.