Hydrogen is a clean, effective and renewable energy, and is a satisfactory alternative for fossil fuels in the future. Bio-hydrogen by dark fermentation from organic wastes is attractive due to energy recovery and environmental cleanup at the same time, making hydrogen a real green energy. This paper focused on the effects of ecological factors such as temperature, pH, substrat, metal ions and end products on bio-hydrogen generation, and discussed the condition of dark fermentation processes of hydrogen production.