This experiment was conducted to study the effects of dietary arginine level on growth performance, nutrient digestibility, nitrogen metabolism and serum biochemical indexes of female blue foxes in growing period.Sixty female blue foxes aged (60±5) days with similar body weight were randomly divided into 6 groups with 10 replicates per group and 1 fox per replicate, and they were fed experimental diets which 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) arginine on the basis of a basal diet, respectively.The adaptation period lasted for 10 days and the formal period lasted for 63 days.The results showed as follows: 1) dietary arginine level had a significant effect on the average daily gain (P<0.01) which in group Ⅴ was the highest and in group Ⅰ was the lowest; the dry matter intake in group Ⅴ was significantly lower than that in group Ⅰ (P<0.01); the feed/gain in groups Ⅴ and Ⅵ was significantly lower than that in group Ⅰ (P<0.01).2) Dietary arginine level had significant effects on the digestibility of crude protein and ether extract (P<0.01).The digestibility of crude protein in group Ⅴ was significantly higher than that in group Ⅰ (P<0.05), and the digestibility of ether extract in group Ⅵ was significantly higher than that in other groups (P<0.01).Dietary arginine level had no significant effects on the digestibility of dry matter and carbohydrate (P>0.05).3) The nitrogen intake in group Ⅴ was the lowest and in group Ⅰ was the highest, and the significant difference was found in groups Ⅰ and Ⅴ (P<0.01).The fecal nitrogen output in group Ⅴ was decreased by 11.73% compared with group Ⅰ (P<0.05).The nitrogen retention in group Ⅴ was increased by 20.54% compared with group Ⅰ (P<0.05).The net protein utilization and biological value of protein in group Ⅴ were both the highest, which were significantly higher than those in group Ⅰ (P<0.01 or P<0.05).Dietary arginine level had no significant effect on urea nitrogen output (P>0.05).4) Serum alkaline phosphatase activity in group Ⅳ was significantly higher than that in other groups (P<0.01).Serum urea nitrogen content in groups Ⅴ and Ⅵ was significantly higher than that in groups Ⅰ, Ⅱ and Ⅲ (P<0.01).Dietary arginine level had no significant effects on serum alanine aminotransferase and aspartate aminotransferase activities (P>0.05).Considering all indexes, the 0.8% is considered to be an optimal supplemental level of arginine in the diet (dietary total arginine level is 2.41%) for female blue foxes in growing period which can improve average daily weight, and decrease feed/gain and serum urea nitrogen content.It is recommended that the arginine intake of each female blue fox in growing period is between 4.22 to 4.24 g/d.