In the light of the characteristics of south-to-north water transfer project in the east of China, the requirements of step pump stations of the project for pump units are analyzed. According to the application situation of low head large pump units and the available technique level, the reliability, maintainability, circumstance protection, investment, performance cost, reasonable capacity, pump type, motor type, axial type and key structures of the pump units are advanced to promote benefits of the project. The results are worth referencing to plan, equipment selection and performance maintenance of the project.