Most of the indigenous peoples of Bangladesh have been living in the Chittagong Hill Tracts (CHT) especially in Bandarban district since a long time ago. The accompanying study “Assessing the ecological declining and environmental degradation situation of hilly area” has been conceived for a comprehensive understanding the ecological declining and environmental degradation status of the people living in the Bandarban. The purposes of this study are to estimate the present status of food availability and environmental degradation of the Bandarban District, to develop a system dynamics model to simulate food security and environmental degradation at upazila and district level and to address the different management strategies and development scenarios. This research is carried out using primary data including field observation, questionnaire survey, GPS data, official documents etc. and published documents. A total of 150 households were chosen from 7563 households using Raosoft sample size calculator. Advance statistical software i.e. SPSS has used for data entry and analysis. The research found that about 24.67% of the household said that the main disaster risk is land slide. And they are facing this frequently of several years. Other natural disasters are flood (44.67%), cyclone (18.67%), flash flood (10.66%) etc. Last 5 years they have to face flood at higher amount (44.67%), land slide 20.67% and flash flood 12.67%. So the disaster risk is increasing. People blamed increasing disaster risk due to hill cutting soil erosion, deforestation, faulty agricultural practices, etc., for the land- slides. Govt. and NGOs reduce hill cutting and take measures to reduce deforestation