Abstract: Backgrounds Long-term high intake of sodium chloride would result in high blood pressure,however the mechanism is uncertain.It is not conclusive whether there exists a retention of sodium and water,and it is still unclear regarding the interactions between sympathetic-adrenal system（SAS）and renin-angiotensin system（RAS）.Objective To analyze the effects of different sodium chloride amounts of intake and water on the blood pressure of Wistar rats.Methods Twenty Wistar rats were randomly divided into 4 groups according to daily different intakes of sodium chloride and water with 5 rats in each group:low intake of sodium chloride with unlimited water supply,low intake of sodium chloride with physiologically-indispensable water（40 mL/d）,high intake of sodium chloride with unlimited water supply,and high intake of sodium chloride with physiologically-indispensable water（40 mL/d）.The intakes of water were measured daily,and urine samples were collected in the metabolic cages in each group.The difference values（D-value）were calculated between the intake of water and the volume of urine daily.Weight and rat tail systolic arterial pressures were measured weekly for a total of 8 weeks.Blood noradrenalin（NE）and angiotensin Ⅱ（Ang Ⅱ）were measured using enzyme-linked immunosorbent assays（ELISAs）8 weeks later.Results The blood pressures in high sodium chloride intake groups with a slow increase of body weight were significantly higher than those of low intake of sodium chloride（P ＜0.01）;the D-value between the intake of water and the volume of urine,and Ang Ⅱ were significantly lower while blood NEs were higher.Furthermore,there exist significant differences in the blood pressures（166.7±2.2）and（156.2±2.3）mm Hg ,NEs（3.5±0.6）and（2.2±0.5）μg/L and Ang Ⅱ（203.5±98.0）and（233.4±101.7）ng/L between high intake of sodium chloride group with physiologically-indispensable water and high intake of sodium chloride group with unlimited water supply（P ＜0.01）.Conclusion High intake of sodium chloride would induce the elevation of blood pressure.However,this process possibly has no relation with the retention of sodium water and excessive activation of RAS system.Instead,the mechanism could be due to the overly excitation of the sympathetic nerve system.