This paper presents a parameters-setting method for the synchronization of pumped-storage units under the pumping condition. The synchronizing process of the units is analyzed and the synchronizing parameters-setting principle of generating units is referred. Finally, the method is educed through mathematical formula derivation. Under the pumping condition, the setting value of the closing pulse leading time and the synchronizing process are both different from those of the generating condition, so the changes of voltage and frequency of pumping condition during closing pulse leading time are deduced. Then, the setting method of the allowable voltage difference, frequency difference and closing angular phase difference could be obtained. The parameters-setting method in this paper provides the theoretical foundation for synchronizing parameters setting of pumped storage unit. It is significant for decreasing the synchronizing impact current and heightening success rate of synchronization.