As much as 97% of electricity sources in Bangka Belitung Province use fossil energy sources, where the remaining 3% is a new renewable energy source. In addition, electrical energy sources are still imported from the outside region and have not relied on local energy sources. Meanwhile, the Government of Indonesia has initiated various regulations for energy development in each region. Policies issued by the government aim to improve energy security and energy independence. In its implication, a study on energy security in Bangka Belitung Province has never been conducted. So, it becomes important to define and assess the level of energy security in this province. In the process of assessing the level of energy security, a combination of qualitative and quantitative methods was conducted. Qualitative methods are carried out with literature studies to determine the dimensions and indicators. While the quantitative method is carried out by measuring the energy security index in accordance with the assumption of PLTS penetration. The results of the indicator measurements are normalized because they have different units and polarities. Meanwhile, the weighting values representing each dimension and indicator are multiplied by the relative value of the indicator. Aggregation of dimension values is carried out to obtain the energy security index in the evaluation year according to the scenario developed. From the results of this study, the 2025 RUPTL scenario can increase Bangka Belitung’s ESI from 0.423 to 0.609. In 2050, the RUPTL scenario can increase ESI from 0.556 to 0.646.