Fecal samples of cubs and adults of giant pandas were examined to determine the effects of diets on the diversity and dynamics of gut bacteriophages. Enterobacteria phage, Salmonella phage, Escherichia phage, Shigella phage, Klebsiella phage, and Lactococcus phage were found to be dominant in both cub and adult samples. Citrobacter phage, Cronobacter phage, Pectobacterium phage, Erwinia phage, Dickeya phage, Erwinia phage, Enterococcus phage, and Pseudomonas phage were more abundant in adults, while Lactococcus phage, Streptococcus phage, Lactobacillus phage, and Leuconostoc phage were more abundant in cubs. The abundance and diversity of the majority of phage species were increased in pandas with age. There was an increase in the abundance of Pectobacterium phage and a decrease in the abundance of Lactobacillus phage, Leuconostoc phage, Bacillus phage, and Streptococcus phage in adults. As cubs and adults of giant pandas have different dietary habits, these observations suggest a significant effect of diets on the composition and abundance of gut bacteriophages in giant pandas.