Salinity is an important ecological factor in the environment. It not only affects growth but also survival rate, osmotic pressure, and non-specific enzymes in juveniles of E. sinensis in the Yangtze Estuary, the effects of salinity on survival rate, osmotic pressure, and non-specific enzymes of juvenile were studied. Juveniles were added to circular glass fiber cylinders with different salinity levels (0, 4, 8, 12, 16, 20, and 24) and maintained under the following conditions:average water temperature 23-24; pH 7.2℃ -7.8; and average DO>5 mg/L. The survival rate, tissue homogenate supernatant Na⁺, Cl^-, and K⁺ concentrations, Na⁺-K⁺-ATPase activity, oxyhemoglobin content, and the activities of total superoxidase (SOD), alkaline phosphatase (AKP), and phenoloxidase (PO) were analyzed after 3 days of the experiment. The results showed that the salinity 8 experimental group had the highest survival rate and hemocyanin content, which were 89% and (0.253±0.023) mg/mL, respectively, and were significantly higher than those of other experimental groups (<0.05) but were minimized in the freshwater and salinity 24 groups. Na⁺, Cl^-, and K⁺ concentrations, Na⁺-K⁺-ATPase activity, and non-specific immune enzyme activity were divided into three stages. Firstly, these indicators decreased significantly with increasing salinity (0-8), gradually increased with higher salinity (8-12), and finally stabilized at the highest salinity (12-24). It had its lowest index values in the salinity 8 experimental group, the concentrations of Na⁺, Cl^- and K⁺ were (40.897±1.700) mmol/mL, (8.340±2.130) mmol/mL, and (1.842±0.158) mmol/mL, and the activity of Na⁺-K⁺-ATPase was (3.153±0.735) U/mg, and the activities of SOD, AKP, and PO were (129.026±3.496) U/mg, (1.326±0.173) U/mg, and (16.366±0.065) ng/mL, respectively. Together, the results revealed that the juveniles were highly adaptable in low salinity (4-8), whereas fresh water and high salinity water weakened its osmotic regulation and immune defense function. The goals of this study were to reveal the physiological characteristics during feed-bait migration and provide a scientific basis for resource conservation and environmental assessment of juvenile .