Solid acid catalyst NaHSO ₄·SiO ₂ was prepared by sol-gel method from NaHSO ₄·SiO ₂, TEOS and isopropyl alcohol, and applied in the biodiesel production with the esterification reaction of oleic acid and methanol. The factors including catalyst calcination temperature, NaHSO ₄ loading, reaction time, catalyst amount, reactants molar ratio methanol to oleic acid on the biodiesel yield were investigated. The experimental results show that solid acid catalyst NaHSO ₄·SiO ₂ has high catalytic activity, the esterification reaction conversion can reach 95.19% under the following optimal conditions: catalyst calcination temperature 200 ℃, NaHSO ₄ loading 15.0%, reaction time of 5.0 h, n(methanol)∶n(oleic acid)= 10∶1 and weight ratio of catalyst to oleic acid 10∶1. 