To recognize the way of akinete differentiation in cyanobacteria, studies on the differentiation of akinete of Anabaena azollae are presented. The results are as follows: 1 Akinete differentiation in Anabaena azollae begins at the late exponential phase of growth in batch culture. The process of akinete differentiation is heavily suppressed in the culture depleted of Fe or Ca ion, while phosphorus deficience induce the formation of akinete in culture. The induction by phosphorus deficience can be enhanced by the increase of nitrate concentration. The total frequence of akinetes of the culture increased up to 41.35%, 42.2% and 68.8% in the presence of 1mM 5-methl-DL-tryptophan, 10mM L-arginine and 10mM DL-phenylalanine, separately. 2. Light limitation probably is one of most important external factors triggering the initiation of akinete formation in A. azollae. The relationship between light and organic carbon source in regulating akinete differentiation is explored. In certain condition, organic carbon source influence the process of differentiation of akinete in the way as light do. It is suggested that the failure in akinete formation of some cells in culture condition is caused by the lack of cell reserve accumulation. 3. It is found that the DNA content of akinete is three times more than that of vegetative cell. The enzyme activities of glucose-6-phosphated-hydrogenase (G-6-PDH), hexokinase (HK) and α-amylase are sharply declined during the course of differentiation, however, the activity of catalase are changed gradually during the process. The paper proposed that akinete differentiation in A. azollae is mainly controlled by the interaction between energy limitation and accumulation in cell. The possible mechanism of akinete differentiation in cyanobacteria is discussed in the light of these findings.