Objective: To investigate the inhibitory effects of lactate and osmotic stress on Lactobacillus casei Zhang and to find solutions. Methods: The organic salt stress and osmotic pressure stress were created by using sodium lactate， ammonium lactate and sodium chloride， respectively， to determine the concentration of complete inhibition and plot the osmotic resistance curve， and the physiological damage to LCZ and the protective effect of compatible solutes were observed by measuring the density of the bacteria， the number of viable bacteria and cell damage. The key factors of osmotic pressure elevation were explored by batch culture and constant pH batch culture， and the effect of osmotic pressure reduction was achieved by diluting the fermentation broth， and the changes of bacterial density， viable bacterial count and dry weight yield of the samples were measured after dilution. Results: L-proline has a significant protective effect on LCZ biomass accumulation and cell activity under hypertonic environment， and the optimal addition amount is 2 g/L. The diluted fermentation broth treatment has a significant effect on the density and viable count of bacteria in constant pH supplemented culture. The final fermentation broth OD600nm and viable bacteria count could reach 19.68±0.429 and (3.439±0.110)×1010 CFU/mL， which were 1.61 and 1.46 times of the undiluted treatment， respectively. Conclusion: L-proline can alleviate the activity damage of LCZ under hypertonicity to a certain extent， and reducing the osmotic pressure at the later stage of fermentation by diluting the fermentation broth treatment can greatly improve the fermentation level and cell activity， which can provide reference for industrial production and application.