Abstract:GND coded glucose 6phosphate dehydrogenase (G6PDH) is a key enzyme in the pentose phosphate pathway. In order to understand molecular information of GND and mechanism in response to drought stress, we cloned GND by designed specific primers based on sequences of homologous cyanobacteria species. The sequence was analysed by bioinformatics methods, and the differential expression of GND and G6PDH activities of N. flagelliforme under drought stress were also discussed. The results indicated that: (1) the full length of GND is 1 431 bp(GenBank access number: KX553955). Nucleotide sequence and deduced amino acid sequences of GND from N. flagelliforme were similar to that of N. punctiforme PCC 73102 with similarities above 96% and 98%, respectively. Ile is the most hydrophobic in site 26 and 27, but Arg is the most hydrophilic in site 302. Thr, Ser and Tys have 19, 18 and 5 phosphorylation sites, respectively. Secondary and tertiary predicted structures of G6PDH were made up of α helix, β sheet, β turn and random coil. (2) GND was expressed in E. coil then a 47.23 kD heterologous protein was observed and tested by MALDITOFTOF/MS. (3) GND expression at the transcription level and G6PDH activity were all gradually increased under drought stress. The results provided a foundation for further research in GND expression and regulation of N. flagelliforme in response to drought stress.