Abstract: Objective To explore the significance of cellular DNA content analysis in diagnosis of histological grades of benign and malignant tumor of central nervous system. Methods The cellular DNA content and DNA ploidy of tumors were measured by quantitative imageanalysis with histochemistry techniques. Results The DNA content and DNA Indes (DI) in astrocytoma were that: gradeⅠ4.11±0.75，1.44±0.28；gradeⅡ 4.52±1.20，1.71±0.34；gradeⅢ6.35±1.82，2.54±0.44；gradeⅣ7.07±1.32，3.13±0.59。) medulloblastoma 5.61±2.10，2.33±0.83；3.18±0.94，1.35±0.26， There were no remarkable difference between medulloblastoma and grade Ⅲ astrocytoma, acorstic neurioma and grade I astrocytoma, grade I and grade Ⅱ astrocytoma groups. But between other groups, there were remarkable difference (P<0.01). Conclusions Cellular DAN content analysis is a useful way to make histological diagnosis of benign and malignant tumor of central nervous system.