Abstract: The strain HLAB0143 with acid resistant ability was screened from Xuzhou natural fermented pickles. The strain could grow under pH2.5. The strain was identified Lb. casei by morphological, physiological and biochemical characteristics and 16sDNA sequence analysis. Orthogonal experiments were carried out based on single factor experiments, the optimal growth parameters for this strain was determined, the temperature was 37℃, the original pH was 5, inoculation amount was 1% (v/v) . The acid mechanism was studied, glutamic acid decarboxylase activity was one of the mechanism of resistance low acid environment.