In order to reduce auxiliary power consumption and improve unit efficiency, frequency conversion transformation was implemented for the condensate pump in Huaneng Yuhuan power plant. The solution was suggested for the restrictive factors of depth frequency conversion of condensate pump which were the seal water of steam feed pump and the desuperheating water of low-pressure bypass in turbine. The operation tests were carried out for the condensate pump after depth frequency conversion, which included opening experiment of water-feeding main valve in deaerator, regulator parameter tuning of main pipe pressure in the condensate with frequency conversion control, switch test between variable frequency pump and general pump for condensate pump, frequency conversion adjustment test for condensate pump with condensate system fault occurred, and so on. The economic benefit analysis show that the depth frequency conversion for condensate pump can decrease the throttling loss to a minimum, and further reduce the condensate pump’s current and speed, when deaerator’s main valve is fully open, which can reach the effective energy saving.