The growth of Lactobacillus bulgaricus,Lactobacillus casei,Lactobacillus plantarum and Streptococcus thermophilus,pH,lactic acid content and their relationship were researched during the cherry tomato juice fermenta-tion.Furthermore,the cooperation of bacteria was also studied.The results showed that:(1) pH values of these four strains could reach 4.0,3.8,4.01 and 4.14 after 21 hours fermenting,respectively.(2) Streptococcus thermophilus has the shortest delay period and its logarithmic phase can be reached after 3 ～ 6 hours fermenting.It was also con-firmed that the bacteria mixture contains Streptococcus thermopilus can shorten the fermentation period remarkably.The lactic acid content of cherry tomato juice fermented by Lactobacillus bulgaricus and Streptococcus thermophilus was 0.49%,which is lower than the bacteria mixtures contain Lactobacillus plantarum.