This paper presents a typical coprecipitation method to synthesize silicate-substituted calcium deficient hydroxyapatite (SiCDHA). A homogeneous aqueous solution of Ca(NO3)2• 4H2O, H3PO4 and Si(CH3CH2O)4 (TEOS) was used as precursor, and NH3 aqueous solution as precipitator. A series of samples were prepared by adding the precipitator to the precursor then following a general coprecipitation route. The results showed that the so-prepared samples were SiCDHA. SiCDHA was thermal unstable and decomposed to tricalcium phosphate and wollastonite-like phase. These new phases were helpful to improve the bioactivity of sintered SiCDHA ceramics.