Currently, there is little information available to describe the nanostructure of crystal hydroxyapatite, which contributes to influencing the macro characteristics of fluorosis-affected enamel. This research using Scanning Electron Microscopy/ Energy Disperse X-Ray (SEM/ EDX)and Powder X-ray Diffraction (XRD). The results of this study have demonstrated Fluor concentration were higher in fluorosis enamel and the surface increasingly roughness and porous. The a-axis on fluorosis-affected enamel 9.3786 ?, and the c-axis 6.8836 ?. The a-axis on normal enamel 9.4148 ?, and the c-axis 6.8791?. The grain size of fluorosis-affected enamel 19.59 nm and normal enamel 20.30 nm. The microstrain of fluorosis-affected enamel 31.54% and normal enamel was 20%. This study concluded that Fluor, as a mostly electronegative element, decreases the crystallinity and improves the microstrain of hydroxyapatite. These conditions will influence the strength and stability of fluorosis-affected enamel.