The bacterial communities of arthropods play important roles in the growth and development of their hosts, such as by providing nutrition or protecting against parasites and pathogens. However, for Tetranychus truncatus, a major crop pest, very little is known about its bacterial community. To understand the effects of the bacterial community in T. truncatus, mites were fed bean leaves that had been soaked in different concentrations of tetracycline hydrochloride (5 mg to 5 g per L). Antibiotic treatment had a negative impact on the fitness of T. truncatus, decreasing its fecundity and longevity. However, we could not exclude the possibility that the decrease in fecundity was due to a toxic effect of the antibiotic. 16S rRNA genes analyses showed that the antibiotic treatment did not significantly affect the diversity of bacterial species, but it did significantly change their relative abundances. Furthermore, predicted functions of microbiota were also changed with antibiotic treatment and the most abundant genes were related to metabolism. Our research revealed that the antibiotic induced change of bacterial communities mostly decreased the fecundity of T. truncatus, although we couldn't totally exclude the direct toxin of antibiotics on spider mites.