A solid superacid catalyst , SO2 -4 /ZrO2 - SiO2 , was prepared by impregnating the Zr(OH)4 - Si(OH)4 co precipitate with a sulfuric acid solution, then drying and calcinating , in which the Zr(OH)4 - Si(OH)4 coprecipitate was prepared with zirconium oxychloride as zirconia sources, silica solution as silica sources and aqueous ammonia as precipitant , respectively , then drying at 110 ℃. The results from XRD and surface area measurements indicate that the addition of SiO2 strongly changes the structure of SO2 -4 /ZrO2 , hence greatly increases its surface area. The effect of preparation conditions such as concentration of sulfuric acid and calcination temperature on the catalytic performance of SO2 -4 /ZrO2 - SiO2 substituted for sulfuric acid for the esterification of n - butanoic acid with n - butyl alcohol was studied. The results show that the yield of butyricbutyl using the SO2-4 /ZrO₂ - SiO₂ catalyst prepared with the concentration of H2 SO4 by 1. 0mol /L and the calcination temperature of 550℃ is higher than 90 % when the molar ratio of butyl alcohol to butanoic acid is 1. 2 ∶1 and without addition of entrainer , which is superior to the reported results obtained using SO2 -4 /TiO2 - WO3 and TiSiW12 O40 / TiO2 catalysts under comparable experiments.