Thirty-nine healthy Ganxi goats aged 4 months with similar body masses ((15.25±0.46) kg) were divided into three groups with 13 goats in each group. Goats in experimental groups Ⅰ, Ⅱ, and Ⅲ were fed diets with ratios of non-fibrous carbohydrates to neutral detergent fiber content(NFC/NDF) at levels of 0.9, 1.2, and 1.5, respectively. The experimental period lasted for 70 days, consisting of a 10-day adaptation period followed by a 60-day formal trial period. At the conclusion of the feeding period, slaughter performance, blood biochemical indicators, rumen fermentation parameters, rumen bacterial gene expression levels, intestinal morphology, and muscle nutritional components of the Ganxi goats were determined to investigate the effects of dietary NFC/NDF levels on these metrics. Results indicated that the pre-slaughter live mass of goats in Group Ⅱ was significantly higher than that in Group Ⅲ, being 1.09 times that of Group Ⅲ. On day 10 of the formal trial period, blood glucose(GLU) concentration of goats in Group Ⅲ was significantly higher than that in Group Ⅱ, being 1.31 times that of Group Ⅱ. On day 30 of the formal trial period, the serum total cholesterol(TC) concentration of goats in Group Ⅰ was significantly higher than that in Group Ⅲ, being 1.42 times that of Group Ⅲ, while the GLU concentration of goats in Group Ⅲ was significantly higher than that in Group Ⅱ, being 1.15 times that of Group Ⅱ. On day 60 of the formal trial period, the TC and triglyceride(TG) concentrations of goats in Group Ⅰ were significantly higher than those in Group Ⅲ, being 1.23 times and 1.53 times those of Group Ⅲ, respectively, while the GLU concentration and alanine aminotransferase(ALT) activity of goats in Group Ⅰ were significantly lower than those in the other two groups. The rumen pH of goats in Group Ⅰ was significantly lower than that in Group Ⅱ, while total volatile fatty acids and propionate concentrations of goats in Group Ⅰ were significantly higher than those in Group Ⅱ, being 1.07 times and 2.48 times those of GroupⅡ, respectively. The relative gene expression levels of Ruminobacter amylophilus, Fibrobacter succinogenes and Butyrivibrio fibrisolvens in goat rumen in Group Ⅱ were significantly higher than those in the other two groups, with the lowest levels observed in Group Ⅰ, while the relative gene expression levels of Ruminococcus albus, Prevotella ruminicola, Lactobacillus spp. and Ruminococcus flavefaciens in goat rumen in Group Ⅰ were significantly higher than those in the other two groups, with the lowest levels observed in Group Ⅲ. Group Ⅰ goats exhibited significantly lower mass fractions of muscle glycine, histidine, total amino acids, non-essential amino acids, and sweet amino acids compared to the other two groups, and alanine mass fraction of goats in Group Ⅰ was significantly lower than that in Group Ⅱ. Meanwhile, Group Ⅱ goats had significantly lower muscle methionine mass fraction than those in the other two groups. No statistically significant differences were observed among the three groups in intestinal morphological indicators, muscle nutritional components or fatty acid mass fractions. In conclusion, diets with different NFC/NDF levels could regulate ruminal microbial community structure in Ganxi goats, thereby influencing fiber and protein degradation, which affected rumen fermentation and improved pre-slaughter live mass. Under the conditions of this study, an NFC/NDF level of 1.2 was found to be optimal.