The effect of molar ratio of methanol to oil, temperature and space velocity (SV) on pre-esterification of Tung oil was carried out in pilot-scale fixed bed reactor, with solid acid catalysts. The molar ratio results showed the maximum acid value reduction efficiency (90.21%) was obtained at the molar ratio of 8:1, the acid value decreased sharply to 0.70 g kg(-1) of KOH. And esterification reaction attained balance when space velocity was enough, so 0.029 h(-1) was optimal space velocity. Furthermore, activity of reactant and rate of reaction increase with temperature increased, and the maximum conversion was achieved at 65 C, the acid value of Tung oil could be reduced to 1.4 g kg(-1) of KOH. (C) 2009 Elsevier Ltd. All rights reserved.