Acacia nilotica has been worldwide recognized as a multipurpose tree species and widely distributed in tropical and subtropical Africa naturally. At the beginning of 1969, this species was introduced to Baluran National Park, East Java Indonesia. Then shortly, it becomes invasive plant, and dominates the savanna area of park. It also inhibits the growth of native grasses as main components of Baluran Savanna. This phenomenon can make the park landscape imbalance and lead to tend a savanna extinction and disorder of ecosystem structure, especially for wildlife animals ; many herbivores and endangered carnivores. investigating of vegetation dynamics was accomplished by placing 50 plots in each savanna ecosystem (total 150 plots). The results showed the savanna ecosystem has been transformed from the original form. Changing in vegetation composition and structure was significantly observed by the evidence of decreasing biodiversity. All the ecosystem types were categorized into moderately invaded for each 10m x 10m. While in 1m x 1m showed different condition where Invaded area was identified to the highly invaded category. It can be concluded that this ecological condition was caused by allelophatic effect and the other ecological factors of A.nilotica plant species.