Abstract： Objective To invastigate the observation and fluid infusion nursing of hyponatremia following head injury. Methods To retrospectively analysis 42 cases of head injury complicated with hyponatremia,through correct reasonable fluid infusion and oral adninistration or nasal feeding salt water, continously monitoring blood serum natrium change. Results In these 42 patients, blood serum natrium is less than 130 mmol/l,urine natrium is more than 20 mnol/L just after head injury. Through correct administration of sodium, the patient blood serum natrium changed to nornal. Conclusion Closely observe the patients consciousness, vital signs, monitorring blood serum natrium change, are helpful to diagnose and treat hyponatremia. Emphasize the overall nursing of the patients, can decrease the nortality and morbidity .