Abstract: This research evaluated the effect of dietary neutral detergent fiber (NDF) level on blood immune cells and intestinal characteristics of Rex rabbits at weaning in order to define the relationship between dietary NDF and intestinal health, and provide a theoretical basis for diet formulation for Rex rabbits at weaning. Fifty-six newly weaned rabbits (35 d) were randomly assigned into 4 groups (14 rabbits per group with each rabbit considered a replicate for statistical purposes), and the groups received different diets with NDF levels of 29%, 33%, 37% and 41%, respectively. The experiment comprised a 5 d pre-trial period and a 28 d experiment period. Diarrhea rate and mortality were recorded during the entire trial. At the end of the trial, 6 rabbits from each group were slaughtered for sampling of blood and intestinal indicators. It was found that with increasing dietary NDF, the count of white blood cells did not differ between treatments (P>0.05), while the lymphocyte count was significantly increased (P<0.05). sIgA+ cell counts in the duodenum and jejunum were increased with dietary NDF level (P<0.05), but this trend was not observed in the ileum (P>0.05). Moreover, the total number of intestinal bacteria was similar for the 4 treatments (P>0.05). Bacteroides was increased at lower MDF with the 33% NDF group being significantly higher than the other groups (P<0.05). Cecum Lactobacillus and Escherichia coli numbers generally decreased with increasing dietary NDF level: specifically, the 29% NDF group got the highest Lactobacillus count while 41% NDF group had the lowest E. coli number (P<0.05). Furthermore, cecum pH was increased with dietary NDF level while diarrhea rate and mortality were decreased. In summary, among tested treatments, the 41% dietary NDF level optimized the intestinal health of Rex rabbits at weaning.