Under the background of high-intensity fattening,probiotics have gradually become wide-ly used feed additives.It can inhibit the proliferation of pathogenic bacteria,maintain the microeco-logical balance in the digestive tract,and improve the host immune function.In order to screen lac-tic acid bacteria strains with potential probiotic effects,23 acid-producing strains were isolated from rumen fluid of healthy Duolang sheep by CaCO3-MRS solid medium.Safe strains were re-screened through primary screening and hemolysis tests.Acid tolerance tests and bile salt tests were used to screen the strains that were relatively adapted to the rumen environment.The survival rate of the strain M2 was 93.80％under pH3.0 and 59.72％under bile salt concentration of 0.30％and the survival rate is higher than other strains under high temperature conditions.Subsequently,morphological observation,molecular biological identification,testing of pathogen antagonism,antibiotic tolerance analysis,growth characteristics detection and other methods were used to fur-ther explore the characteristics of the strain.The results showed that the strain to be tested was Gram-positive bacillus.After 16S rRNA gene sequence comparison,the strain was identified as Lactobac illus salivus,which could be used as a candidate strain to develop probiotics.The research results laid a foundation for its application in Duolang sheep breeding.