The growth of Bacillus coagulans,Lactobacillus plantarum and Lactobacillus rhamnosus were studied,and the content variation and relationship of acidity,reducing sugar,p H value,viable cell count and amino nitrogen were researched during the caulis dendrobii juice fermentation. By measuring the speed of acid production,viable cell count,the sense and flavor of product etc.,the lactobacillus being applicable to ferment Caulis dendrobii juice were screened. The results showed that,after 48 hours fermentation,acidity of three samples fermented by Bacillus coagulans,Lactobacillus plantarum and Lactobacillus rhamnosus reached 7. 85 mg / m L,6. 93 mg / m L and 7. 66 mg / m L,respectively,and the total sugar content reduced by 78. 64%,67. 28% and 76. 85%. Considering the speed of acid production and the ability to produce acid,Bacillus coagulans and Lactobacillus rhamnosus was better than Lactobacillus plantarum.