The circulating cooling water system is based on water as a cooling medium, and a cooling water recycling system. In the condenser, the circulating water to the steam turbine exhaust steam is condensed, taking the steam release of latent heat of vaporization, and therefore the formation of a high degree of vacuum in the condenser, which reduces the turbine exhaust pressure turbine ideal enthalpy drop increase power increase. Need to consume large amounts of water in the process of electricity production, China is a serious lack of water resources in the country, so local conditions the choice of the circulating water cooling system is very necessary in this context were the 600MW unit of thermal power plants circulating water cooling system piping design, the dual-pump dual-process closed loop water cooling system, there are three main problems involved in this design: the design of the mainline pipe diameter; design and a circulating pump of the condenser cooling pipe diameter the power of choice. The first is the diameter of the system in charge of road design, assume a diameter, and by calculating the flow losses within the mainline piping, to find a current loss of control in the design range that corresponds to the diameter. Followed by calculation of the design of condenser cooling tube diameter, according to the thermal power plant condenser tube selection guide "the cooling water flow rate and the cooling pipe material, assuming that the diameter and wall thickness calculation for Condenser pipe size, and condenser water resistance HEI calculation method to calculate the loss of the water side, to find the corresponding diameter of the losses in the design range. Final choice of the circulating pump power.