Abstract： Objective To research the of etiology,pathogenesis,diagnosis,and treatment.Severe head trauma research with hyponatremia.Methods A retrospective hospital in January 2008-2009 December severe head trauma 28 patients with hyponatremia in the diagnosis and treatment of patients.Results SIADHS,4 cases diagnosed by water treatment,24 patients were serum sodium,23 patients were diagnosed CSWS at 10 d treatment for expansion,and to added sodium,improved,1 cases of primary brainstem injury MODS concurrent and death.Conclusion cerebal saltwasting syndrome of inappropriate secretion of antidiuretic hormone secretion with abnormal syndrome pathogenesis and treatment measures are completely different,grasp type and improve outcomes have very important significance.