With the great development of aerospace enterprise, space infection is a new subject to be investigated.Attaching to astronauts and spacecrafts, microorganisms may go into outer space and grow under microgravity environment and then threaten the health of astronauts and the safety of aircrafts.This paper summarizes the biological characteristic changes of microorganisms in simulated microgravity and spaceflight environment, including the aspects of the microbial morphology, growth rate, cellular metabolism, virulence, viability and gene expression, and aims to further investigate biological effects of simulated microgravity and spaceflight on microorganisms.