Abstract: This experiment tried to isolate Andbaena azollae directly from Azolla leaf cavities after surface sterilization, then grew it on various culture media and conditions.More longer green-keeping periord of isolated Anabdena azollae was found in alien medium suplemented with organic N and C, micro-aerobic(1% O2, 99% N2)condition to compare with N-free medium and aerobic condition.The isolates underwent a limited multiplication in above growing condition but failed to continue the further multiplication.These cyanobacteria were antigenically identical to the endosybionts of Azolla.