Inverted microscope,atomic force microscope(AFM),CCK 8 and flow cytometer were used to study the toxicity of curcumin on human hepatoma HepG2 cells qualitatively and quantitatively.The AFM results indicated that curcumin could induce the deformation change of HepG2 cells to varying degrees.The volume and height of the cells decreased with the increase of cell deformation,whereas,the mean roughness(Ra),mean square root roughness(Rq) and granularity distribution of HepG2 cell surface increased with the increase of cell deformation.Through detecting the mechanical property of the cells by AFM,it was found that the relative adhesion force of the cell surface decreased from （7084±2557） pN to （2998±396） pN when 40 μmol/L curcumin was incubated with HepG2 cells for 24 h.By means of CCK 8 assay,it was found that the HepG2 cell viability was related with the reaction time and drug concentration.When 20-80 μmol/L curcumin were incubated with HepG2 cells for 24 h and 48 h,respectively,the cell viability declined from（722±38）% to （106±23）% and （536±27）% to （87±18）%,respectively.In addition,the result of cell cycle analysis by flow cytometer showed that curcumin could block the HepG2 cell in G2/M phase.The results obtained above are of significance to the visual diagnosis of drug induced early apoptosis in cancer cells,and to the study of the drugs-cells interaction.