Abstract: The rate of wastewater treatment was only 3% among the 580 thousand villages of China in 2008 and also only reached 8% in 2012. The total amount of untreated decentralized wastewater was as 1.5 times as centralized sewage treatment in city and county. Environment pollution problem of decentralized wastewater has become more and more seriously and it needs urgently to resolve. This paper described the concept and components of decentralized wastewater treatment, and pointed out that biological treatment was usually used. The research developments, principles and advantages and disadvantages of various wastewater treatment technologies were analyzed from 3 aspects of anaerobic, aerobic and natural biological treatment. Wetland, stabilization pond, earthworm eco-filter, eco-toilets and other natural biological treatment technologies have many advantages including a low construction cost, low environmental impact, suitable for local conditions, flexible, etc, and are becoming new, economical, environmental friendly and dominant technologies for decentralized wastewater treatment. Finally the research direction of decentralized wastewater treatment technologies was put up forward.