For improving the economic benefit of the generation unit with ACC (air-cooled condenser) in summer season, a peak-load condenser system was updated for the ACC system.Optimization of the peak-load condenser operation was studied using the site test and system simulation methods.Based on the site test data, certain characteristic performance parameter was calculated such as cleanness factor and etc..Final optimized operation scheme was studied using the simulation software for various ambient conditions.It is shown that, for the example unit, based on the current equipment conditions, for most of the weather conditions except for winter, the peakload condenser with one cooling pump in operation can improve the unit performance.