Abstract: The artical introduce deaerator principle,the application and classification of deaerator in thermal power generation unit,briefly describe the structure and process of different deaerator,analysis and comparison the differences between conventional deaerator and built-in deaerator.In combination with the output of atomizing nozzle,the selection of 1 350 MW super-capacity unit deaerator is studied,one-fix and three-slide surpots、two-big and one-small multiple nozzles built-in deaerator is recommend.it meets the demand of feed water deaeration and can save equipment investment,providing ideas for the development of the unit to very large capacity.