Abstract: It remains a mystery why the highly complicated species diversity is formed and sustained in microbial community in low-dose ionizing radiation (LDIR). Based on prophase investigation and experimental observation,in the research,a hypothesis is first proposed in this research that different levels of delay effect on population growth resulting from exposure to LDIR can greatly mitigate competitive exclusion,inducing and sustaining the species diversity in microbial community. The kinetic model of microbial community succession in the environment of LDIR was obtained by introduction of delay effect into classic Lotka-Volterra competition model,and then a great deal of digital simulations were carried out to elucidate the generation and maintenance mechanisms of species diversity induced by LDIR. The results provide a theoretical basis for understanding the dynamic mechanism of microbial community succession in LDIR environments.