The present paper carries out a cost benefit analysis of centralized wastewater reuse systems in Beijing. This study consists of two parts: financial analysis and economic analysis. The financial analysis is made from the point of view of plant manager, in which financial benefits and cost is calculated. The economic analysis is made from the point of view of society, in which the economic, environmental and social benefits and cost are determined. The results of financial analysis show that the financial benefits are larger than cost, which means the centralized wastewater reuse systems are financially feasible. It implies that the investment on centralized wastewater reuse systems is profitable. The results of economic analysis show that the ratio of benefit to cost is larger than 1, which means the centralized wastewater reuse systems are economically feasible. It implies that centralized wastewater reuse systems have positive effects on the society. From the point of view of plant manager, centralized wastewater reuse systems could operate in a long term, while from the point of view of government or society, the centralized wastewater reuse systems are worth to be promoted.