The CaCO₃/biopolymer composite materials have been prepared by a two-step synthesis. The biopolymer was synthesized from chitosan and acrylic acid in supercritical carbon dioxide, then a large scale of novel flowerlike structured calcite CaCO₃ on the biopolymer has been synthesized for the first time by the following process of mineralization. The well-defined flowerlike morphology consisting of orderly and regular petals could be tailored by controlling the reaction time. The morphology evolution of CaCO₃ was investigated by the XRD, FTIR and SEM. Moreover, the prepared CaCO₃/biopolymer composite materials were further characterized by ¹H NMR, HRTEM, SAED and XPS, respectively. The experimental results show that the petal possessed a single crystal structure and consisted of stackings of (18). Interestingly, the product is sensitive to the lower laser power by Raman spectra. Based on experimental results, the growth process of formation of a special shape for CaCO₃ was also speculated, which indicates that acrylic acid and chitosan played an important role in forming substrates and in following further mineralization of CaCO₃.