Abstract: The alkaline conditions for extraction of natural dye from tea and dyeing on silk fabrics with the resulting extract were studied. Natural dye from tea was extracted with Na2CO3 solution. Factors exerting influence on extraction results such as Na2CO3 concentration, extraction temperature, extraction time and factors exerting influence on dyeing results on silk fabrics such as dyeing pH, dyeing temperature, dyeing time, Na2SO4 concentration were discussed. It was found that the dyed silk fabrics with Na2CO3 solution extracts of tea had better colour strength than the dyed silk fabrics with extracts obtained in water. The optimum conditions for the extraction were as follows: Na2CO3 8g/L, extraction temperature 90℃, extraction time 40min. The optimum conditions for the dyeing on silk fabrics were as follows: pH value 4.00, Na2SO4 40g/L, dyeing temperature 90℃, dyeing time 60min, bath ratio 50:1. The dyed silk fabrics with Na2CO3 solution extracts have higher fastness properties. The washing fastnesses were obviously improved by mordanting.