Abstract: The suggested discharge for 3rdstage river closure of TGP is 12 200 m\+3/s ,and the final water drop is 5.77 m,thus,the closure work will be the largest o ne of comprehensive difficulties in the world.On the basis of primary test resul ts on integrated closure model of TGP with a scale of 180 and the experience o f Gezhouba Project's river closure,some problems,including 3rdstage closure sc hemes,measures preventing the lose of riprap blocks in moving water,structure fo rm of bedding course and its construction period selection,etc.,are discussed.It is considered that:end dumping with double dykes is a preferable scheme;bedding course horizontally filled in advance with concrete blocks and stone materials for roughening the river bed may effectively prevent the lose of dumped materia l s;to guarantee the success of construction of bedding course,its construction pe riod should be selected at winter 2001 to spring 2002.At present,the bedding cou rse structure formed by 10 tconcrete tetrahedrons and large block stones weigh ing 3-5 t may meet the requirement for stubility in flood season.But it is need ed further study to be optimized. .