This study aims to determine the effects of supplementation minerals [phosphorus (P) and sulfur (S)] and cassava leaf meal to ammoniated palm leaves and frond rations on the feed digestibility and performance of beef cattle. This study used a randomized block design which divided 20 male Simmental cattle into 5 treatment rations and 4 groups as replications. Treatment NG, the control, was a native grass+ concentrate, PLF= Palm leaves and fronds+ concentrate, PLFM= PLF+ 0.27% phosphorous (P) and 0.4% sulfur (S), PLFC= PLF+ cassava leaf meal (5%) and PLFMC= PLFM+ cassava leaf meal (5%) Compared to other cows, cows that get PLFMC consume more but are no different (P> 0.05) from cows that consume NG. Feed digestibility from PLFM and PLFC is lower (P< 0.05) than PLFMC and NG. Daily gain and feed efficiency of NG were not different (P> 0.05) from PLFMC. Feed conversion ratio (FCR) from NG and PLFMC is lower (P< 0.05) than PLFM and PLFC. It can be concluded that PLFMC can replace native grass 100% and produce the best digestibility and performance of beef cattle.