Abstract: The main pipe system is adopted in circulating water system by Mawan General Power Plant. In summer it can satisfy the requirement for the circulating water of two units with full load when three water circulating pumps operate, and it makes obvious economic benefit. In this paper its regulation process was introduced, and the economic benefit getting from adoption of the regulation was analyzed, the conclusions which the operation mode is economic and feasible were obtained.

Key words: water circulating pump operation, vacuity degree, net income