A novel Mg-containing alpha-tricalcium phosphate (alpha-TCP) bone cement with excellent wetting compressive strength and suitable setting time has been developed in this work. Mg-substituted octacalcium phosphate (Mg-OCP) crystals with the special morphology was prepared by homogeneous precipitation method, and used to modify the alpha-TCP bone cement. Mg2+ was successfully introduced into OCP structure, and the filaments/sheet-like morphologies of OCP were obtained by changing the Mg2+ concentration. As added in the alpha-TCP cement matrix, the effects of Mg-OCP on the wetting compressive strength, setting time and microstructure of the cement system were studied. The addition of Mg-OCP shortened the setting time of cement pastes with the minimum setting time of 15 min, and enhanced the wetting compressive strength of the hydrated cement products with the highest wetting compressive strength of 36.86 MPa. This work highlights the special morphologies of Mg-OCP induced by Mg2+ substitution, which made an effect on the hydration reaction of alpha-TCP cement; Furthermore, Mg-OCP was supposed to improve the condensation capacities and mechanical properties of alpha-TCP cement system as a novel cement admixture. (C) 2017 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.