Calcium phosphate fiber was synthesized by homogeneous precipitation method using urea as precipitation agent. Effects of the reactant concentration and hydrothermal temperature on the calcium phosphate morphology and composition were studied using SEM, FTIR and XRD. It is found that fine octacalcium phosphate（OCP）fiber can be synthesized when the reactant concentrations are 0.167 mol/L for Ca（NO3）2, 0.1 mol/L for （NH4）2HPO4, and 0.6-0.7 mol/L for （NH2）2CO, respectively, with the initial reactant solution pH value around 2.2, hydrothermal temperature 90 ℃ and termination reaction at pH value around 5.0. At very low urea concentration, the product size distribution is highly inhomogeneous, however, at an excessively high concentration the product becomes larger and shorter and a mixture of OCP and hydroxyapatite （HA）. Increasing the hydrothermal temperature is favorable to the fast precipitation of OCP, higher productivity and finer product.
