Abstract: Two weak postacidification Lactobacillus delbrueckii subsp.bulgaricus strains which were screened from KLDS- DICC were regarded as the research subjects. The fermentation characteristics of these strains were studied, including abilities of producing acid, producing flavoring substances, physical properties and post acidification during the storage period to assess whether they had the potential to be yoghurt starter. Results demonstrated that KLDS1.1011 and KLDS1.1006's acid- producing ability was lower than KLDS1.9201, while the yogurt's acidity after 24 h storage at 4℃ was higher than 70°T which satisfied the requirements of GB19302-2010.Besides, the yoghurt fermented by KLDS1.1011 occurred very low postacification during storage at 4℃ and 20℃for 21 d, discharging less whey, best textural features and yielding higher acetaldehyde.Therefore KLDS1.1011 has greater value to study more.