The invention discloses a carbon fiber composite material bone plate and a preparation method thereof. The preparation method specifically comprises the following steps of: coiling, stacking and laying up carbon fiber prepreg cloth according to the design, preheating, pre-forming, preheating and molding; cooling, feeding into a demolding table, opening the mold, taking out the product, cleaning and drying; performing CNC machining on a bulk material according to a bone plate design drawing so as to form a bone plate blank; and performing biosafety coating treatment on the surface of the obtained bone plate blank. The bone plate is high in biocompatibility; by virtue of biological coating, the biosafety of medical implants is improved; the bone plate is close to real bone strength; the various mechanical parameters are equivalent to those of bones, the adaptation problem is solved, and a stress-shielding effect caused by stress concentration is avoided; the carbon fiber composite material bone plate has excellent X-ray penetrability, can meet the nuclear magnetic resonance testing requirements and is suitable for batch production and low in cost.