An 8-week feeding trial was conducted to evaluate the effects of dietary potassium (K⁺) on growth performance, nitrogen metabolism and osmoregulation of the Pacific white shrimp () reared in low-salinity well-water (4 ppt) with a Na⁺/K⁺ of 41.6. A total of 720 juvenile shrimps, with an initial body weight of 0.372 g ± 0.006 g, were randomly divided into six groups. Six experimental semi-purified diets were formulated, containing 0.59, 0.96, 1.26, 1.48, 1.74 and 2.17 g (K⁺) /(100 g diet) as feeding treatments and designated as D0, D1, D2, D3, D4 and D5 group, respectively. After a 56-day feeding trial, the results showed that the weight gain rate (WGR) of shrimps fed with D2 [1.26 g(K⁺)/(100 g diet) ] was the highest (<0.05), but there was no significant difference between D2 and D0 (control). The protein efficiency ratio (PER) of D1 showed the highest value among all treatments (<0.05). There were no significant differences in body moisture, crude fat, ash and protein content (> 0.05) among all treatments. However, body potassium content in D1 had the significantly highest value and D5 the lowest in all treatments (<0.05). increased, the oxygen consumption rate of shrimps fed with the 1.48 g (K⁺)/(100 g diet)<0.05), while the ammonia-N excretion rate of D2 was also the significantly lowest (<0.05). The D1 diet group had the significantly lowest arginase activity (<0.05). However, there were no significant differences in hemolymph ammonia, urea or uric acid levels among all treatment groups ( values decreased and then increased significantly with increased dietary K⁺ (-K⁺-ATPase activity revealed a reverse trend and shrimps fed with the 1.48( K⁺)/(100 g diet) (D3 group) had a relatively higher value than other treatment groups (<0.05)., hemocyanin levels tended to increase and then decrease significantly (<0.05). There were no significant differences between hemolymph osmolarity or potassium ()/(100 g diet) can improve dietary protein utilization and maintain a balance in the nitrogen metabolism and osmoregulation of + of 41.6. Excessive supplementation of potassium [1.5%, total 2.17 g (K⁺)/(100 g diet)] may disturb metabolism and limit the growth of .