The present application and existing problems of pump in chemical works are introduced, then, pump’s controlling principle, especially which with frequency conversion technology, is mentioned. The energy-saving controlling of frequency conversion on pump is studied in detail based on the study of the starting, operation and redundancy configuration of pump. The result shows that energy can be saved on the starting, operation and redundancy configuration of pump with the frequency conversion technology. The energy-saving through frequency conversion controlling is related to actual running efficiency of pump and it has limitation. When pump’s running efficiency is high, the energy-saving result is unapparent. While pump’s running efficiency is low, the energy-saving result is outstanding.