higher plant such as lettuce CELSS system in wet cultivation device dependent。photosynthesis efficiency of Azolla and vegetable comparative test results show that：in the different growth stages，the photosynthesis efficiency of lettuce is not the same as； 5 days after planting of the lettuce the photosynthesis efficiency no as the Azolla；15 days after planting of lettuce the photosynthesis efficiency considerable as Azolla。In existing raises in the wet cultivation device dependent to plant 2-3 kind of different vegetables, the preliminary conformity testing, still did not discovery between lettuce and Azolla has the harmful incompatibility。