Abstract: Ｏｂｊｅｃｔｉｖｅ：The mortality rate of  with  maintenance hemodialysis (MHD) patients is still much higher than that of the healthy population of the same age.Cardiovascular and cerebrovascular diseases are the leading cause of death in MHD patients.Previous studies have found that increased chronic fluid overload was associated with hypertension,left ventricular hypertrophy,and heart failure.In this study,the body composition monitor (BCM) was used to detect the hydration status in MHD patients and analyze the correlation between the results and the death of MHD patients and hospitalization due to cardiocerebrovascular events.Ｍｅｔｈｏｄｏｌｏｇｙ：76 patients aged 18～75 years were included in this study,who were treated with MHD for more than 3 months and 3 times every week at March 2014.BCM was used to assess the hydration status of patients.They were followed to March 2019.The death and the first hospitalization for cardiocerebrovascular events during the study period were the study end point.Cox proportional hazard regressions were used to determine the correlation between hydration index and the end points,events and ROC curve was used to analyze its predictive ability for prognosis.Ｒｅｓｕｌｔｓ：Endpoints events occurred in 25 of 76 patients during a 5year followup period.The patients were divided into 2 groups according to end point events.Compared with the group with out end point events,the elderly age (P<0001),a higher proportion of  diabetes mellitus (P=001) and cardiovascular disease (P=0001),higher levels of IL6 (P=0013),and the more extracellular fluid by height correction(ECW/H) (P=0002),the higher ECW and total body water(TBW) ratio (P=0002) were found in the end points group.Multivariate COX regression analyzed revealed that the ECW/H were independently correlated with endpoint events (HR:2179,95%CI:1299～3657).ECW/H had predictive value for poor prognosis of patients（AUC 0731，P=0001).Ｃｏｎｃｌｕｓｉｏｎ：Extracellular fluid volume expansion suggested by BCM is independently associated with death and cardiovascular adverse events of MHD patients.Therefore,maintaining patients′ ideal hydration status according to BCM assessment is beneficial to improve the prognosis.