Esterification of lactic acid with butanol catalyzed by Amberlyst-type ion exchange resin and sulfuric acid was carried out in a batch reactor under temperature ranges of 100 ~ 130 ℃. The reaction rate was significantly influenced by water contents (wt%), alcohol/lactic acid mole ratio, kinds of catalysts and reaction temperature. Esterification of the lactic acid with butanol is promoted by removing residual water continuously using recycle reactive distillation(above 100℃). The presence of water strongly inhibits the conversion of lactic acid to butyl lactate due to equilibrium-limited reaction. Other operation parameters were also investigated in terms of lactic acid conversion.