Abstract: Based the brake horsepower characteristics of low specific speed centrifugal pump and the required features of pumps used for agriculture, the concept of non - overload centrifugal pumps is conceived. The history and present status of non-overload centrifugal pumps both at home and abroad are introduced. The paper presented a summary of its theoretical derivations and experimental results. The operating characteristics and hydraulic design principles are discussed and the present problems and their possible solutions are analysised