OBJECTIVE： To explore the effect of administration timing of mannitol on efficacy and related indexes of patients with moderate cerebral hemorrhage. METHODS： Data of 280 patients with moderate cerebral hemorrhage being treated with mannitol were divided into super-early group （65 cases）， early group （97 cases） and extension group （118 cases） was analyzed retrospectively according to administration timing. All patients received conservative medical treatment， ntrition brain cells and other symptomatic and supportive treatment. Based on it， super-early group received mannitol within 6 h of cerebral hemorrhage， early group received mannitol within 6-24 h， and extension group received mannitol more than 24 h. Clinical efficacy， incidence of hematoma enlargement， mortality， incidence of continued bleeding/rebleeding and incidence of adverse reactions in 3 groups were observed. RESULTS： The incidences of hematoma enlargement and mortality in early group and extension group were significantly lower than super-early group， the differences were statistically significant （P＜0.05）； but there were no significant differences between early group and extension group （P＞0.05）. The total effective rate in early group was significantly higher than super-early group and extension group， the incidence of continued bleeding/rebleeding was significantly lower than super-early group and extension group， the differences were statistically significant （P＜0.05）； but there no significant differences between super-early group and extension group （P＞0.05）. CONCLUSIONS： Based on conventional treatment， mannitol shows better efficacy for patients with moderate cerebral hemorrhage within 6-24 h of cerebral hemorrhage than those in super-early or extension. It can reduce continued bleeding/rebleeding incidence， and has equivalent safety.