Calcium phosphates were synthesized in simulated body fluid(SBF) which had the same calcium phosphate ratio with the human blood at 37℃ with different values of pH. The mineral phase and micromorphology of the products were studied by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FTIR), scanning electron microscope(SEM) and transmission electron microscope(TEM). The results indicate that mixture of crystalline dicalcium phosphate dihydrate(DCPD), octacalcium phosphate(OCP), and hydroxylapatite(HA) can be formed when the value of pH is 5.9. The DCPD are lamellar crystals with length of 10μm and width of 3μm. The OCP are also lamellar with their length being about 200 nm and the width between 50 nm and 100 nm. The rod-like HA are between 40 nm and 50 nm in length and 20 nm in width. When the value of pH is between 5.9 and 6.4, the length of crystals increases with the increase of pH and the crystals grow along axis c. When the value of pH exceeds 6.4, the product is HA and its length decreases with the increase of pH. When the value of pH ranges from 5.9 to 8.9, the crystallinity of HA decreases with the increase of pH. In the experiment, CO₂ in the air can dissolve in the mineral solution and develop into CO₃^2-, and CO₃^2- can enter the lattices of HA, which makes the composition of the synthesized HA in accordance with the biogenic carbonated hydroxyapatite.