Objective To evaluate the predicting accuracy of revised grading standards of electroencephalography (EEG) in cerebrovascular diseases. Methods EEG was performed on 60 patients suffering from acute cerebrovascular diseases (CVDs) in the hemisphere and the data were recorded continuously. According to 2 different grading standards of EEG (Synek standards and revised standards), these patients were graded, respectively. Results These 2 grading standards of EEG was statistically correlated with the outcome (P<0.05); the higher the EEG grade was, the poorer the outcome was. Logistic regression showed that the revised standards had higher accuracy on the survival and total prediction as compared with the Synek standards. Conclusion The revised grading standards of EEG can demonstrate the changes of CVDs well and improve the predicting accuracy.