In this experiment, citrus peel was used as a material, extracted to obtain the colorant of its own. The dyeability of citrus on textiles in various concentrations and pH conditions, determination of its λ_(max) wavelength and the reproducibility of the natural colorant (citrus peel) by the absorption value at the λ_(max) are all discussed in this article. In addition, three kinds of mordant ferrous sulfate, stannic chloride, copper sulfate are also used in dyeing polyester fabrics with the natural colorant obtained from this experiment, and the apparent concentration, dye-uptake, and dyeing fastness of the specimens are also examined. The results show that the reproducibility of the natural colorant extracted from citrus peel is about 31% in the unit of coefficient of variation. And the ferrous sulfate mordant can have the highest dye-uptake concentration among all the mordants tested while the stannic chloride the best dyeing fastness, about reaching to 4 or 4-5 grade.