This study is aimed to improving extracellular lipase production by Trichoderma strains using oil palm empty fruit bunch (OPEFB) medium on solid state fermentation with the assistance of statistical optimization. Two selected Trichoderma strains (Trichoderma sp.1 and Hypocrea neorufa.1) with high lipase producing potential were employed in a stepwise optimization. Initially, the influence of nutritional (carbon, nitrogen sources, and inducers) and environmental (moisture and temperature) factors on lipase production was evaluated using One Factor-At-A-time (OFAT) method. Next, three most influential factors (Glucose, Urea and Olive oil) resulting from OFAT were optimized for lipase production by Trichoderma sp.1 using the central composite design under response surface methodology. Experiments conducted under optimum conditions (10.38% (w/w) glucose, 0.86% (w/w) urea, and 7.38% (v/w) olive oil) were further improved the lipase production from 0.195 to 0.390 Ug(-1), which is about 2 folds greater than un-optimized condition. This study demonstrated that OPEFB can be utilized as inexpensive substrate for improving the lipase secretion by Trichoderma sp.1.