The objectives of this study were survey and evaluation of the biochemical characteristics of the enterotoxigenic E. coli strain PD17 (ETEC-PD17) and strain TM21 (ETEC-TM21) as well as study on the conditions for preservation, conservation of these microorganisms. The studied result indicated that both strains ETEC-PD17 and ETEC-TM21 shoWed all the typically biochemical characteristics of E. coli. After 20 subculture lifes, these strains showed the biochemical characteristics and stability properties of culture compared with the conservative origin breed. Besides, all the tested strains always kept the ability to produce enterotoxin in the intestine. Biological, chemical, stability characteristics of the strains ETEC-PD17 and ETEC-TM21 were determined. These strains were kept at the different conservat'ive temperatures and durations showed the normal performances. Of which, freeze-dried conservation is an optimized method for microorganism conservation.