Objective To explore the subtype,incidence and duration of delirium in intensive care unit(ICU).Methods From October 2015 to September 2017,we prospectively collected baseline information of 516 inpatients met the inclusion criteria of ICU in Jinhua Municipal Central Hospital of Zhejiang Province.We assessed patients with the Confusion Assessment Method for the Intensive Care Unit(CAM-ICU),and analyzed subtype of delirium and compared the incidence and duration of delirium.Results Among 516 patients,there were 119 cases with delirium along with 23.06％for the incidence.There were 14 cases with delirium in the type of increased activities,61 cases with delirium in the type of decreased activities and 44 cases with delirium in the mixed type.Delirium of 79.83％of patients occurred for the first time when being admitted to ICU between the second day and fifth day with 63.87％for the incidence of delirium night.The duration of delirium was from two to three days accounting for 52.94％.There were statistical differences in the occurrence time of delirium with three subtypes(χ2=11.116,P=0.025).The differences in duration of delirium with three subtypes were also significant(H=24.728,P<0.001).Conclusions Patients' high-incidence period of delirium is from the second day to the fifth day after being admitted to ICU.The occurrence time of delirium has the volatility showing the characteristic of light daytime and heavy night.We should strengthen assessment for delirium of patients to identify and take steps early,so as to reduce the occurrence risk of ICU delirium and shorten the duration of delirium.