The research on producing bioethanol from this rubber wood sawdust waste provides a method for generating green fuel from a cheap, abundant, and currently wasted resource. With the aim of improving the conversion efficiency of bioethanol from rubber wood sawdust, this study combined alkali dilute pretreatment with high pressure to facilitate easier hydrolysis of rubber wood sawdust and fermentation with Saccharomyces cerevisiae. In the study, HPLC and UV-Vis methods were used to determine the composition and content of lignin, cellulose of the raw material before and after pretreatment. Additionally, Saccharomyces cerevisiae yeast was cultured in Sabouraud dextrose Broth (SDB) medium to achieve high cell density prior to use. Simultaneous saccharification and fermentation (SSF) were conducted with appropriate temperature, time, and conditions to optimize the conversion efficiency of cellulose, hemicellulose into ethanol. The pretreatment conditions were optimized for sawdust by soaking in 2% NaOH solution for 24 hours, followed by pretreatment in a high-pressure device at 170°C (7,02 bar) for 1 hour. The results showed that sawdust after pretreatment had an increased cellulose content from 43.20% to 66.63%, with a pretreatment efficiency of 70.53%. The material subjected to pretreatment was proven to be advantageous for the fermentation process, with the resulting solution having bioethanol content of 1.68% vol and a conversion efficiency of 60.32% for the entire process.