In this work， the hop-resistant strain Lactobacillus brevis 49 isolated from the spoiled beer was used as the starting strain to study the extracellular pH， intracellular ATP and chain length， saturation， chain branching， and U/S changes of fatty acids of cell membrane. The results showed that hops had a significant inhibitory effect on Lactobacillus brevis 49， and 60 mg/L was the highest tolerance to hops concentration of Lactobacillus brevis 49. Hops will decrease the extracellular pH of Lactobacillus brevis 49， and high concentration of hops will lead to higher extracellular pH. The amount of intracellular ATP of Lactobacillus brevis 49 under hop stress was an order of magnitude lower than that without hops stress. As the concentration of hops increases， the increase in fatty acid carbon chain length of Lactobacillus brevis 49 cell membrane， especially C20， was much obvious. The average chain length also increases along with the increase of hop concentration； The cyclic fatty acid C19 had a significant increase compared to the control group. When adding the high concentration of hops， the proportion of fatty acid unsaturated fatty acids and branched fatty acids in the cell membrane increases， and the saturated linear fatty acids decreases. Meanwhile， the U/S value also increases together with increase of hop concentration.