To investigate the copigmentations of glutathione and gallic acid on purple yamanthocyanins, the effects of glutathione and gallic acid on the degradation rate, thermal stability and color difference of anthocyanins were studied. The results showed that glutathione and gallic acid could effectively inhibit the degradation of anthocyanin, and the optimal addition amount was 0.03% and 0.2%, respectively. Under that additive quantity condition, the thermal degradations of purple yam anthocyanin in 50 ℃, 70 ℃ and 90 ℃ water bath were in accordance with the firstorder degradation kinetics. Compared with the control group, the degradation rate constant (k) of purple yam anthocyanin decreased after adding glutathione and gallic acid, the halflife and activation energy were improved, which suggests that glutathione and gallic acid can enhance the thermal stability of anthocyanin. Meanwhile, the color difference results indicated that the brightness index (L*) and chromaticity index (a*, b*) of purple yam anthocyanin with the effects of glutathione and gallic acid change slowly, Therefore the color stability is enhanced.