The three types of large tubular pump unit,bulb type,axial-extension type and shaft well type,were analyzed and compared from the aspects of the pump system's hydraulic characteristics,unit's structures and its force characteristics,key components,electric motor's ventilation mode,regulation of pump operation,installation,maintainability,reliability and so on.The three types of tubular pump unit have their own advantages and disadvantages.Combining the characteristics of the actual pumping station project,the selective advices of large tubular pump unit's structure are put forward.The results could provide references to select the bulb tubular pump units.