Oil palm trunk (OPT) is lignocellulosic biomass and renewable waste obtained from palm oil production, and it can be used to produce ethanol. In this study, the ethanol plant was analyzed using Aspen Plus software for process simulation and modeling, based on of 60,000 kg of OPT, while the model inputs were based on data recently obtained in the laboratory. Various pretreatments of OPT are used such as steam explosion, hot water, alkaline hydrogen peroxide, and simultaneous saccharification and fermentation (SSF). All these pretreatments are used to increase the cellulose content and efficiency of getting fermentable sugars from cellulose for conversion to ethanol. The cellulose content was 73.96% by dry wt after treatment, from 38.67% in the original OPT. For the SSF step in a laboratory, treated OPT was used to ferment ethanol for about 60 h, producing an ethanol yield of 0.469 g EtOH g-1 cellulose. This information was used to simulate the SSF unit. Ethanol was purified by extractive distillation using ethylene glycol as a solvent. The simulation of the distillation column comprised 15 stages, the distillate for feeding had mass ratio 0.65, and the reflux mass ratio was 1.4, potentially producing 9,531 kg of ethanol.