The short carbon fiber (Cf) reinforced hydroxyapatite (HA) bio-composite was prepared by an in-situ processing. Mechanical properties and microstructure of Cf/HA were investigated. Structures of HA was analyzed using XRD and fracture surface morphologies of bio-composite were analyzed using SEM. Result shows that grain size of HA under hot pressing sintering (1423K, 35MPa) grow up to approximately 50nm. Bio-composite exhibits excellent mechanical properties when Cf mass fraction is 3%, whose flexural strength and flexural modulus reach the maximum values of 130MPa and 36GPa which surpass common level of nature bone. SEM fracture surface morphologies of Cf/HA shows Cf can be uniformly dispersed in the HA matrix when the mass fraction less than 6%, while when the mass fraction is11%, partial aggregation appears.