The invention relates to a preparation method of a hydroxyapatite coating on the surface of a carbon/carbon composite material. A deposition solution is placed in an ultrasonic atomizing device to generate ultrasonic atomized gas, the ultrasonic atomized gas is carried by carrier gas to flow through the surface of the carbon/carbon composite material, heating is conducted on the exterior of the carbon/carbon composite material through an electromagnetic induction method to deposit a calcium hydrogen phosphate coating on the surface of the carbon/carbon composite material, and hydrothermal treatment is carried out on the carbon/carbon composite material with the calcium hydrogen phosphate coating deposited on the surface to obtain the hydroxyapatite coating. The method has the advantages that the preparation method of the hydroxyapatite coating is simple and easy to operate, the coating has a strong binding force and is uniform, and the hydroxyapatite coating has the functions of inducing bone tissue regeneration and regulating growth and remodeling of bones.