Abstract: In this study, a high-density fermentation process of Halomonas elongate DSM 2581^T was established, which had the advantage of high ectoine production rate. The effects of nutrient components of defined medium on fermentation and metabolism of H. elongata DSM 2581^T were investigated by single factor experiment, Plackett-Burman and Central Composite Design. The results showed that sodium citrate (3 g/L), NH₄Cl (3 g/L) and NaCl (80 g/L) could significantly promote the growth and ectoine production of H. elongata DSM 2581^T. Furthermore, according to the growth and metabolism of H. elongata in the defined medium in a 5 L fermentor, the feeding mode of glucose continuous flow plus and pH feedback control (ammonia water) was established to carry out the high-density fermentation process of H. elongata DSM 2581^T. Salt shock, which increased the NaCl concentration in the fermentation broth from 80 g/L to 130 g/L in the exponential growth phase, resulted in OD₆₀₀ reaching 169.3 after 13 h of fermentation, with ectoine production and ectoine synthesis reaching 20 g/L and 1.54 g/(L·h), respectively. This study provides theoretical guidance for the low-cost and efficient industrial ectoine production.