Abstract: Azollais an important biological component of the Controlled Ecological Life Support System(CELSS),because it can supply O2 and absorb CO2 from the environment,and can be used as fresh vegetable by the astronauts.The aim of this study is to clarify the canopy photosynthesis regular pattern of Azollain simulated microgravity environment,and to lay the foundation of Azollaspace′s application.Azolla was moistly cultured in the controlled airtight cabin of 3D-rotary plant clinostat,which could stimulate space microgravity effect.The canopy photosynthesis characteristics of Azolla were studied by measuring the O2-CO2concentrations in airtight cabin.The results showed that net photosynthesis efficiency of Azollain stimulated microgravity environment had a positive correlation with illumination intensity.When illumination intensity was 7 000lx,the amount of released O2 and fixed CO2by photosynthesis perunit energy consumption was the largest.Azolla net photosynthesis efficiency also had a positive correlation with CO2concentration in cabin,but a negative correlation with O2concentration.Azolla net photosynthesis efficiency was higher than that of normal atmosphere environment especially in an environment that was low in O2and high in CO2.These results showed that Azolla had strong capacity of photosynthetic O2-release,which balanced the O2-CO2concentration inside the cabin to aid the astronauts′survival,further prospect for Azollaspace application.