The reasonable selection of circulating pump configuration and the optimization of operation mode are the key technology of circulation water system in thermal power unit, and the important step of energy saving and consumption reduction. This paper suggested that the optimal operation with multiple load cases of meteorological conditions and load change should be considered at the election stage of circulating pump configuration, in order to achieve the comprehensive optimization of initial investment and operation economy. Taking a 1 000 MW thermal power unit for example, the technical economy was compared between various configuration modes of circulating pumps, and proposed a recommended scheme, based on the optimization results of energy saving in monthly operation.