In order to further improve the transparent thermal insulation of CsxWO3, controllable synthesis of CsxWO3 nanoparticles from cheap and environment-friendly Na2WO4 center dot 2H(2)O and Cs2SO4 by solvothermal method was conducted using different organic acids as reducing agents. The reducibility and reduction mechanisms of citric acid, tartaric acid and oxalic acid were investigated. It has been confirmed that tartaric acid has the strongest reducibility, and could produce the most W5+ and oxygen vacancies in the CsxWO3 products before heat-treatment. The CsxWO3 nanoparticles synthesized with oxalic acid after heat-treatment exhibited the best crystallinity and the visible light transmission was about 10% higher than that of tartaric acid and citric acid. It is significant for the low-cost production of CsxWO3 nanoparticles with higher transparent thermal insulation performance.