It was studied that metal ions affected light-degradation of silk fabric in this paper. The contrast of the weight and the tensile properties of silk fabric treated without or with different concentrations of metal ions (copper sulfate solution and chromium sulfate solution) by different time of light conditions were carried out. The results showed that after the treatment of silk with metal ions solution, the weight gain of the silk fabric increased with increasing the concentration of metal ions solution. There were different changes in the breaking strength of silk fabric treated with different metal ions when subjected to light exposure. In the same light conditions, comparing with the fabric without treatment, the breaking strength of the fabric with copper (ii) ions treatment increased while the breaking strength of the fabric with chromium (iii) ions treatment obviously decreased. Besides, fabric samples with copper ions treatment slowed down the decreasing rate of the breaking strength and fabric samples with chromium ions treatment accelerated the decreasing rate with increasing light exposure time. The results indicated copper (ii) ions had an inhibitory effect on light-degradation of silk fabric, and chromium (iii) ions enhanced light-degradation of silk fabric. Meanwhile, their respective function for fabric increased along with the increment of adsorption values of metal ions on silk fabrics. When being treated with the same concentration of metal ion solution, weight loss of the silk fabric improved and the breaking strength of the fabric decreased with increasing light exposure time, and the two had linear relationship.