The longissimus dorsi muscle of sheep was treated with cold plasma (CP) induced by dielectric barrier discharge (DBD) at different time points (6, 12, 24, 48, 72 and 120 h) after slaughter. By analyzing changes in the color, myoglobin content, fat oxidation, total sulfhydryl content and surface hydrophobicity of samples during postmortem cold storage, the effects of DBD-CP treatment at different time points after slaughter on the color and oxidation stability of mutton at different time points after slaughter were determined. The results showed that DBD-CP treatment at different time points after slaughter had no significant effects on L^* or a^* values of mutton (P > 0.05), but significantly increased the b^* value compared to the untreated control group (P < 0.05). DBD-CP treatment reduced the color stability of the meat and accelerated the deterioration of meat color. DBD-CP treatment at 6 and 12 h postmortem had little impact on the color stability. DBD-CP treatment at all selected time points after slaughter had no significant effect on the myoglobin content of mutton (P > 0.05). The thiobarbituric acid reactive substances (TBARS) value of the DBD-CP treatment group was higher than that of the control group (P < 0.05), and the treatment significantly reduced the total sulfhydryl content in mutton and increased the surface hydrophobicity (P < 0.05). In summary, DBD-CP treatment at 6 to 12 h after slaughter had the most significant effect on stabilizing and maintaining meat color. In addition, it could accelerate the oxidation of myofibrillar protein (MP). Therefore, DBD-CP treatment has potential application value in improving the quality of mutton.