Gut bacteria of insect play important roles in host food digestion, growth and development, immunity and resistance to pathogens. This study aims to reveal the effects of protein levels of dietary on bacterial communities and functional characteristics of intestinal microbiota in male adult Blattella Germanica. It will provide a basis for evaluating the role of the intestinal bacteria in the host nutritional metabolism and health, and developing the attractive biocontrol dietary for cockroach pests. The male B. germanica adults were separately fed with low protein (LP2 group:5%), high protein (HP3 group:65%) diets, or the normal protein level rat food (CD1 group:25%) for 21 days. Then the intestine of B. germanica was seperated under sterile condition and the total intestinal genomic DNA was extracted. The V4 variable region of bacterial 16S rDNA was amplified by high-through sequencing. The intestinal microbiota of B. germanica was mainly composed of Bacteroidetes, Proteobacteria, Fusobacteria, and Firmicutes. The abundance of Bacteroidetes in LP2 group with low protein bait was significantly higher than those in the control CD1 group and HP3 groups with 65% protein bait. LEfSe analysis demonstrated that the abundance of Fusobacterium in the intestinal microbiota of B. germanica (HP3 group) fed with high protein bait was significantly different with those in LP2 and CD1 groups. The function prediction results from Tax4Fun demonstrated that the relative abundance of genes related to energy metabolism in intestinal microbiome of male adults fed with 65% protein bait (HP3) was significantly higher than that in B. germanica fed with 25% protein bait (CD1). And the relative abundance of the gene associated with xenobiotics biodegradation and metabolism, and metabolism of other amino acid functions were also significantly higher than those of B. germanica fed with 5% protein bait (LP2). The results showed that protein levels of the feeding dietary could significantly change bacterial community composition and metabolism of intestinal microbiome in B. germanica.