Abstract: Objective To investigate the effect of low-dose recombinant tissue plasminogen activator(rt-PA)on the prognosis and hemorrhagic transformation of patients with cardiogenic cerebral embolism(CCE). Methods A total of 72 CCE patients with window time of onset within 4.5 h were selected as research objects. All patients had thrombolysis indications and received rt-PA intravenous thrombolysis voluntarily. Simple random number table method was used to divide them into standard dose(0.9 mg/kg)group and low dose(0.6 mg/kg)group, with 36 cases in each group. CT at 24 to 48 hours after treatment were reexamined. The cerebral CT or MRI reexamination were performed to evaluate conditions of hemorrhagic transformation in the two groups. The scores of National Institutes of Health Stroke Scale(NIHSS)score and Barthel(BI)index between the two groups before and after treatment were compared. The modified Rankin(mRS)score of the two groups was compared at 90 days after thrombolysis. Results After 24 hours and 7 days of thrombolysis, NIHSS scores of the two groups were significantly lower than those before thrombolysis, and BI was significantly higher(P< 0.05). There was no significant differences in NIHSS score and BI between the two groups(P>0.05). There were no significant differences between the two groups in the incidence rates of intracranial hemorrhage and other bleeding sites, as well as mortality rate(P>0.05). The mRS scores at 90 days after thrombolysis in the two groups were significantly lower than that before thrombolysis(P<0.05). There were no significant differences between the two groups in mRS score- and the good rate of prognosis at 90 days after thrombolysis(P>0.05). Conclusion It is similar in short-term prognosis and the risk of bleeding transformation of CCE treated by rt-PA for intravenous thrombolysis at low dose of 0.6 mg/kg and standard dose of 0.9 mg/kg, and they are both safe and effective.