Objective To investigate the effect of malignant cerebellar hemorrhage on 3-month prognosis of small spontaneous cerebellar hemorrhage.Methods Clinical data of 380 consecutive patients with spontaneous cerebellar hemorrhage admitted in Emergency Department of the Affil-iated Hospital of Guizhou Medical University,Neurosurgery Department of Jinyang Hospital Af-filiated to Guizhou Medical University,and Neurosurgery Department of the Second Affiliated Hospital of Guizhou Medical University from April 2014 to March 2023 were collected and retro-spectively analyzed,and finally,70 patients who met the requirements of small amount of sponta-neous cerebellar hemorrhage were enrolled in this study.They were assigned into benign cerebel-lar hemorrhage group(43 cases)and malignant cerebellar hemorrhage group(27 cases).Accord-ing to their clinical outcomes in 3 months after onset,they were divided into a good prognosis group(51 cases)and a poor prognosis group(19 cases).General clinical data,imaging data,com-plications,inflammatory indicators and prognosis were collected.After collinear diagnosis was used to exclude factors with collinear influence,the independent correlation between good progno-sis and poor prognosis was analyzed by binary logistic regression model.Finally,ROC curve was plotted to analyze the significant data.Results The maximum diameter of hematoma was signifi-cantly larger in the malignant cerebellar hemorrhage group than the benign group(P=0.021).The patients of the poor prognosis group had larger proportion of malignant cerebellar hemor-rhage,and higher neutrophil percentage,WBC count and NLR than those of the good prognosis group(P＜0.05,P＜0.01).Multivariate logistic regression analysis showed that malignant cere-bellar hemorrhage was an independent predictor of poor prognosis in 3 months(OR=6.218,95％CI:1.140-17.623,P=0.013).The sensitivity,specificity,positive predictive value,negative pre-dictive value and Youden index of malignant cerebellar hemorrhage in predicting the 3-month prognosis of patients were 63.2％,70.6％,44.4％,83.7％and 0.338,respectively,and the AUC value was 0.669.Conclusion Malignant cerebellar hemorrhage is an independent predictor of 3-month prognosis in patients with small spontaneous cerebellar hemorrhage.The patients with malignant cerebellar hemorrhage have poor prognosis than those with benign cerebellar hemorrhage.