The limited key resources of the earth are being depleted by the unlimited desires of human being''s luxurious life style and due to continuous increase in population of the world. Cities are dependent on rural areas and its surroundings, and will be affected due to social, economical, environmental and political changes happened in its surroundings. The purpose of this study is to investigate the depletion of ecosystem resources in Cambodia in general and the depletion of the forest resource in Cambodia in particular and is the main focused area of this research work. This study points out several reasons to the unsustainable ecological environment in Cambodia. This has been identified in this research work that beside of forest resource, other resources (renewable) for example mammals, birds, fish, plants, reptiles, amphibians, wildlife and bio diversity has been in the state of unsustainability. This study has found that Cambodia is still in a critical stage from the urban sustainable development perspective. The Cambodia government, political leaders, army and other authorities are not doing enough to stop depletion of forest resources.