Silica aerogel (SA) particle was synthesized and characterized. The effects of silica content in silicic acid solution and molar ratio of trimethyl chlorosilane (TMCS)/pore water on silica aerogel physical characteristics such as surface area, pore volume, apparent density, and porosity were investigated. We observed that when the silica content increased from 4 to 7% of weight (wt%), the silica aerogel surface area increased from 628.5m2/g to 914.4m2/g and thereafter (>9%). When the molar ratio of TMCS/pore water increased from 0.1-0.4, the silica aerogel’s surface area increased from 816.8m2/g to 924.1m2/g. The highest silica aerogel surface area of 924.1m2/g and porosity of 96.4% were achieved with a silica content in silicic acid of 7.011wt% and TMCS/pore water of 0.4. Finally, silicon aerogel particles applied to water-based paint to improve the thermal insulation was about 1.2 °C with surrounding ambient temperature of 45 °C.