The invention discloses a preparation method of rod-like titanium-containing hydroxyapatite nano crystals. The preparation method comprises the following steps: preparing a calcium nitrate solution with concentration of 0.3mol/L and an ammonium di-hydrogen phosphate solution with concentration of 0.18mol/L; mixing the calcium nitrate solution with the ammonium di-hydrogen phosphate solution according to a mol ratio that Ca/(Ti+P) is equal to 1.667; adding tetrabutyl titanate in the above mixed solution; mixing and stirring on an electromagnetic stirrer; adjusting pH (potential of hydrogen) to be 10 by using NH3.H2O, and heating; filtering and arranging obtained deposit in a table-type oven; drying at 80 DEG C; milling completely in a mortar; and sintering at 500 DEG C, and then sintering at 800 DEG C to 1200 DEG C to obtain the rod-like titanium-containing HA (hydroxyapatite) nano crystals. The titanium enters crystal lattice of hydroxyapatite due to the adding of the tetrabutyl titanate, so that the thermal stability of the HA is improved, and the high-temperature decomposition of HA is effectively inhibited. The HA does not decompose even at the high temperature of 1200 DEG C. Compared with the rod-like HA nano crystals synthesized without adding the tetrabutyl titanate under the same condition, the crystals are significantly refined and even without gathering phenomenon.