Objective:To explore the effect of different blood sodium levels on the condition and prognosis of patients with severe craniocerebral injury.Methods:A retrospective cohort study was conducted on 150 cases of severe craniocerebral injury admitted to Zhangye People′s Hospital Affiliated to Hexi University from January 2020 to October 2022. According to the five blood sodium values measured on the first day after admission and during the peak period of brain edema (2-4 days after injury) and 7 days after injury, 102 cases of blood sodium metabolic disorder, 43 cases of low sodium group: average blood sodium value<135 mmol/L, 59 cases of high sodium group: average blood sodium value>145 mmol/L. The characteristics of sodium ion metabolism imbalance and the relationship between serum sodium level and Glasgow coma score (GCS), Glasgow prognosis score (GOS) and APACHE Ⅱ score at 2 weeks after injury were analyzed. Measurement data with normal distribution were represented as mean±standard deviation ( ± s), and comparison between groups was conducted using the t-test. count data were expressed as cases or percentages(%), and comparison between groups was conducted using the Chi-square test. Results:The imbalance rate of sodium metabolism in the acute phase after injury was 68.00%(102/150), including 57.84%(59/102) of hypernatremia and 42.16%(43/102) of hyponatremia. The imbalance rate of sodium metabolism at 7 days after injury was significantly higher than that immediately after injury. Hypernatremia occurred earlier than hyponatremia and lasted longer than hyponatremia ( P<0.05). There was no correlation between the low sodium group and the scores of GCS ( R=0.523), GOS ( R=0.367), APACHE Ⅱ ( R=-0.453) ( P>0.05), but the scores of GCS ( R=-0.448) and GOS ( R=-0.486) were negatively correlated with the blood sodium level of the high sodium group ( P<0.05), and the high sodium group was positively correlated with the scores of APACHE Ⅱ ( R=0.477, P<0.05). Conclusions:Patients with severe craniocerebral injury are often accompanied by blood sodium disorder. Hyponatremia can be corrected in a short time and has no effect on the patient′s condition and prognosis. However, hypernatremia seriously affects the recovery of consciousness, prognosis and quality of life of the injured.