Kepok banana peel is a waste product from the processing of kepok banana which can be used as an alternative in animal feed. Low crude protein and high crude fiber become the main problems in the utilization of kepok’s peels. One way to improve its quality is by fermentation. The starter of fermentation used is EM4. The purpose of this research was to determine the effect of dose and length of fermentation against nutritional content of kepok’s peels. This research was designed using completely randomized design factorial with 3 replications and continued using the duncan test. The kepok’s peel were given EM4 at doses of 1, 3, and 5% and then fermented for 3, 5, and 7 days. The results of this research showed that the dose of 5% and 5 day fermentation time were optimal and efficient to increase water and crude protein content and reduce levels of dry matter and crude fiber of banana peel. There was no interaction between dosage and fermentation time for each research parameter.