Abstract: A carbonation process was developed to coat Al(OH)₃ on aragonite whisker. Al(OH)₃ coating was obtained in a suspension,which contained 3Cao·Al₂O₃·6H₂O(C₃AH₆)-NaOH prepared by adding Ca(OH)₂ to NaAlO₂ aqueous solution.The CaCO₃ whiskers coated with fine particles of Al(OH)₃ were prepared by blowing CO₂ gas into the suspension.The formed Al(OH)₃ adhered to the CaCO₃ fibers as the substrate.In order to coat α -Al(OH)₃ on aragonite whisker , the pH value of the solution must be higher than 10.5.The formation of C₃AH₆ and complexation of calcium carbonate molecule with C₃A were the domain factors to get single aragonite phase whisker. Micro-analysis demonstrated that the existence of Al(OH)₃ crystal coating on the surface of aragonite-type calcium carbonate whisker.After the coated whiskers were treated strongly in an ultrasonic water bath.Al(OH)₃ still adhered to the CaCO₃ whiskers well.The reaction mechanism was also mentioned in this paper.