Abstract: Wool fabrics dyed with natural dyes──acutissima shell are studied. Four metal ions are selected. Three different mordant dyeing methods are used and dyeing experiments with different additives are carried out. The results indicated that the fabrics colour is varied with metal ions and mordant dyeing methods. The fabrics used with pre-mordant dyeing method have greater value of colour and better colour fastness. The colour shade is varied with the additive concentration ratio and the fastness could commonly achieve to grade 3. The IR analyses showed that when wool fabrics are mordant dyed, the metal ions may be coordinated with S-O bond, carboxyl, amide, etc. in wool to form coordination bond. The fabrics colour fastness is improved.