Abstract: In order to investigate the influence and its mechanism of lactic acid bacteria fermentation on the new type of coagulant-free fermented tofu during storage, this study used brine bean curd as a control to compare and analyze the changes of microorganism, color, pH and other indexes of the two kinds of bean curd at different storage temperatures.The influence of lactic acid on the membrane potential of spoilage bacteria of bean curd was analyzed by flow cytometry, and the mechanism of long shelf life of fermented bean curd by lactic acid bacteria was discussed.The results showed that the fermented bean curd by lactic acid bacteria could be stored at 4,10 and 25 ℃ for 14,5 and 2 d, respectively, which were about 2 d longer than that of brine bean curd.During storage at 10 ℃,the number of lactic acid bacteria and spore were significantly lower than that of the control, and the change of pH and color ware slower than that of the control.The number of spore in the brain and molded products of bean curd without coagulant were significantly lower than that of the control, and the content of organic acids, especially lactic acid in bean curd was 3 times than that of the control.Lactic acid has a great influence on the membrane potential of Enterococcus faecium,and can delay the growth and reproduction of Enterococcus faecium.