Objective:To evaluate the value of related characteristic of CT and MR images in differentiating malignant from benign orbital tumors. Methods:Seventy-nine cases with orbital lesions confirmed by CT,MR and pathological examination were enrolled in this study. The tumors,side,size,shape,margin,location,number of affected quadrant,bone destruction,T1 and T2 signal,homogeneity of T1 and T2 signal,enhancement pattern,and CT value were determined. Using single variate analysis and multivariate logistic regression,the correlation between the above mentioned factors and benign or malignant tumors was analyzed. Results:Seventy-nine cases included 49 benign cases and 30 malignant ones. Single variate analysis indicated that tumors,shape,margin,location,bone destruction,and T2 signal bore a close relationship to the benign and malignant orbital tumors. The multivariate logistic regression analysis showed that bone destruction and iso-intense on T2 weighted image were the risk factors of malignant orbital tumors. Conclusion:CT and MR can accurately locate the tumors in the orbit. If combined with bone destruction or iso-intense on T2 weighted image,the orbital lesions might be strongly suspected to be malignant .