This experiment was conducted to study the effects of methane supplementation in low protein diets on growth performance, nutrient digestion and metabolism of growing blue foxes. One hundred and five health male blue foxes at the age of 9 weeks with an average body weight of (2.21±0.60) kg were randomly assigned into 7 groups with 15 replicates per group and 1 fox per replicate. The blue foxes in 6 experimental groups were fed the 30% protein level basal diet (low protein diet) supplemented with 0 (group Ⅰ), 0.2% (group Ⅱ), 0.4% (group Ⅲ), 0.6% (group Ⅳ), 0.8% (group Ⅴ) and 1.0%( group Ⅵ) methine, respectively. The blue foxes in control group were fed the 32% protein level diet (suitable protein diet). The pre-test lasted for 7 days and the trial lasted for 45 days. The results showed as follows: the final body weight (body weight of the 45th day) in the groups Ⅴ and Ⅵ was significantly higher than that in the other experimental groups (P<0.01), but was not significantly different compared with the control group (P>0.05); at the 16th to 30th day, the average daily gain in the groups Ⅳ, Ⅴ and Ⅵ was significantly higher than that in the group Ⅰ (P<0.05), but was not significantly different compared with the control group (P>0.05); at the 31st to 45th day, the average daily gain in the groups Ⅴ and Ⅵ was significantly higher than that in the other experimental groups (P<0.01), and that in the group Ⅴ was also significantly higher than that in the group Ⅵ and control group (P<0.05). The dry matter output in the groups Ⅴ and Ⅵ was significantly lower than that in the other experimental groups (P<0.01), but was not significantly different compared with the control group (P>0.05); the dry matter digestibility in the group Ⅴ was significantly higher than that in the groups Ⅰ, Ⅲ and Ⅳ (P<0.05), but was not significantly different compared with the control group (P>0.05); the protein digestibility in the groups Ⅴ and Ⅳ was significantly higher than that in the groups Ⅰ, Ⅱ and Ⅲ (P<0.05), but was not significantly different compared with the control group (P>0.05); the fat digestibility in the group Ⅰ was significantly lower than that in the other groups (P<0.05), but no significant difference was found among the other groups (P>0.05). The cystine output in the groups Ⅴ and Ⅵ was significantly higher than that in the groups Ⅰ, Ⅱ and control group (P<0.01); the cystine digestibility in the group Ⅵ was significantly higher than that in the other groups (P<0.01), but no significant difference was found between control group and group Ⅴ (P>0.05); the methine digestibility was increased with the methine supplemental level increasing, and that in the group Ⅵ was significantly higher than that in the other groups (P<0.05 or P<0.01), but no significant difference was found between control group and group Ⅴ (P>0.05). Total nitrogen output in the group Ⅳ was significantly lower than that in the groups Ⅰ, Ⅱ and Ⅲ (P<0.05), but no significant difference was found among the other groups (P>0.05); the nitrogen deposition in the group Ⅴ was significantly higher than that in the other groups (P<0.01), but no significant difference was found among the other groups (P>0.05); the net protein utilization in the group Ⅴ was significantly higher than that in the other groups (P<0.05), but no significant difference was found among the other groups (P>0.05). In conclusion, considering all indices of this experiment, when 0.8% methane is supplemented in the low protein diet with 32% protein level, that is, when the dietary methane level is 1.14%, growing blue foxes' methane requirement can be met. In this case, the blue foxes have the optimum growth performance, protein digestibility and nitrogen deposition.