With the development of smart meters, a real-time pricing (RTP) demand response is becoming possible for households in distribution networks. The power flowcan be bidirectional in distribution networks which become smarter with distributed generators (DGs). It is expensiveto import electricity from the generation far from load centers because of the cost of power loss and network use,so that it is more economical to use electricity generated bylocal distributed generators. Therefore, in order to curtailoperating costs of distribution networks, this paper proposes a model of economic optimization conducted bydistribution network operators. The electricity purchasing costs for distribution network operators are minimized byoptimizing electric power from transmission systems and local distributed generators. Further, based on price elas-ticity, the formulations of load demand considering RTP are proposed with economic optimization of distribution networks. The economic optimization problems are resolved by an interior point method. The case study shows that peak load demand can be reduced about 3.5% because the household RTP and electricity purchasing costs of distribution network operators can save 28.86 ￡ every hour.