This invention relates to a preparation method and equipment of graphite and catalyst composite for a kind of synthetic diamond. Firstly, graphite particles shall be placed into the heating chamber for pre-heating; secondly, the heated graphite particle will be fed into the coating room with vibrator or agitator and steam of carbonyl metal complex is input for coating; finally, the coated graphite particles are fed into a cooling and passivation room for cooling and passivation of the discharging materials or enter a next round of heating and coating. The surface of each graphite particle is plated with metal layer which can promote the crystal nucleus growing into perfect diamond crystal.