The objective of this research was to preparation of nanosilica from bagasse by untreated and treated with hydrochloric acid (HCl) using precipitation method. Initially, the the bagasse was treated with HCl and all of bagasse (treated and untreated bagasse) were calcined at 700 ^oC. The bagasse ash was obtained and then was used to prepare nanosilica . From the x-Ray Fluorescence Spectrometer (XRF) results, it was found that HCl affected on silicondioxide or silica content in both sugarcane bagasse ash and sugarcane bagasse nanosilica. Untreated sugarcane bagasse ash showed 57 % of silica content whereas 79 % of silica contained in sugarcane bagasse ash treated with HCl. Then, nanosilica prepared from both untreated and HCl treated sugarcane bagasse ash with precipitation method gave 70 and 77 % of SiO₂, respectively. However, x-ray diffractometer (XRD) results clearly observed that both nanosilica  from sugarcane bagasse ash were amorphous structure similar to commercial silica. Finally, all of silica morphology were analyzed using scanning electron microscope (SEM). It was found that, nanosilica obtained from untreated and treated bagasse with HCl displayed similar particle sizes.