To develop synthesized coralline hydroxyl apatite (CHA) bone graft- substitute and measure its physical and chemical characteristics. Methods: The CHA bone graft- substitute was synthesized from natural mineral-coralline through hydrothermal exchange process. This process was designed and developed independently by the authors. Its physical and chemical characteristics have been determined and studied using various techniques including Scanning Electron Microscopy (SEM), electron microscope image processing, scanning electron microscope energy spectrography; chemical analysis, ICP-AES, X-ray diffraction, etc. Clinical trials have been conducted.Results: Independently developed CHA bone graft-substitute is white in color; its porosity is 25.87%-53.58%,which is approximate to that of human bones and original coral. It is larger than 3-4 in hardness by Mohs hardness scale and the compressive strength ranges from 4.87 to 12.31 MPa. The chemical compositions of the CHA are 53.13%-64.09% CaO and 35.52%-46.48% P2O5. CaO/P2O5 is 1.143-1.804. ICP-AES analysis detected twenty-four trace elements including Pb, Co, Ni, Ba, Mn, Cr, Th, V, Cu, Ti, K, Mo, Zn, Mg, Nb, Be, Sc, Al, Sr, Na, Li, etc. Ca, P,K, Na, Al and Sr are relatively high while the rest are less than n-n×106, which is acceptable by human body. The REE level in the CHA bone measured by ICP-MS is 1.433×10-9-2.212×10-9, which is within the acceptable range for human beings. Conclusions: The process of synthesized CHA bone graft-substitute is an innovated independently developed method and concept. Its color, porosity and chemical composition are similar to those of human bones;therefore it has very good biocompatibility and excellent conductivity. Sixty clinical cases have proved that CHA bone graft-substitute has a strong bone-forming ability, no toxicity, no side effect, and better sacralization. It is a fine substitute for bone transplantation.