Silica as one of the most abundant minerals in the earth's crust that has many applications in various industries. With the expansion of various industries, the use of silica derivatives has grown tremendously. One of the most important derivatives of silica is amorphous and crystalline Nano silica which is used in various industries including paint, rubber, pharmaceutical, cosmetic and food industries. Various processes are used to produce Nano silica and much research has been done on the development of these processes. One of the most available and cheapest Nano silica production processes is the co-precipitation process using silicate precursors. Therefore, in this study, the process of producing Nano silica from sodium silicate by co-precipitation method was investigated. In this study, using the CCD response surface method, the experiment was designed and the effect of temperature, sulphuric acid concentration, water to sodium silicate ratio and final pH of the solution on the physical and chemical properties of amorphous Nano silica were investigated. The accuracy of the obtained results was analysed by ANOVA statistical method. Then, the effect of temperature and time of calcination process on the phase structure and crystal size of crystalline Nano silica was investigated. The results of BET analysis show that increasing the temperature and decreasing the ratio of water to silicate increases the average diameter of the pores. On the other hand, with increasing temperature, decreasing water to silicate ratio and increasing pH, the total volume of pores increases. Also, increasing the temperature reduces the specific surface area and increases the ratio of water to sodium silicate, leading to increasing the specific surface area of ??amorphous Nano silica particles. On the other hand, according to the TEM images of nanoparticles, the average particle size was estimated to be 20 to 25 nm. Examination of X-ray diffraction pattern of crystalline Nano silica shows that in certain temperature and time conditions, it is possible to produce crystalline Nano silica with Tridymite, Cristobalite structure or a combination of these two phases. key words Amorphous Nano silica, Co-Precipitation method, ANOVA statistical analysis, Calcination, Specific surface area, Phase structure