In this study Nibea albiflora juveniles with the average weight of (5.0±1.4) g and the average length of (8.3±0.8) cm were divided into 3 salinity groups including salinity 23 as the control group and salinity 9 and 16 as the stress groups. Fish samples were collected on the 0, 1st, 3rd and 7th day. To evaluate the effects of low salinity on the ion regulation and respiratory metabolism of N. albiflora, we tested the changes in activities of Na+/K+-ATPase (NKA), Ca2+-ATPase, H+-ATPase, lactate dehydrogenase (LDH) and succinate dehydrogenase (SDH) in gills, and the level of cortisol in the serum. In response to the low-salinity stress, the NKA activity increased significantly (P<0.05), and the Ca2+-ATPase activity decreased after a slight increase in the beginning, and the H+-ATPase activity first increased and then recovered to the initial level. The enhanced activities of NKA, Ca2+-ATPase and H+-ATPase could provide more energy for the ion transport to maintain the dynamic balance of the osmotic pressure. The cortisol level in the serum fluctuated significantly (P<0.05) during the low-salinity stress, and the cortisol levels of salinity 9 or 16 group increased alternately. The LDH activity in the gill increased significantly (P<0.05), and the activity of the salinity 9 group was higher than that of the salinity 16 group. The SDH activity in the gill frist increased and then decreased, and the activity of the salinity 9 group increased significantly on the 7th day (P<0.05). Environmental stress would affect the normal aerobic respiration of N. albiflora. Along with the osmotic adjustment, the need of oxygen increased, which may significantly enhance the SDH activity. Noticeably, two experimental fishes died in the salinity 9 group during experiment. The feeding and activity of N. albiflora juveniles in the salinity 16 and 23 groups were normal，whereas they were impaired in the salinity 9 group. Our results suggested that low salinity could have significant effects on the ion regulation and respiratory metabolism of N. albiflora. Excessively low salinity may overwhelm the adaption ability of N. albiflora and cause harm to the health of the fish.