Abstract: Following points have been pointed out:(1) South-to-North Water Transfer Project in China(SNWTP) is not only a water resources project,but also a eco-environment project.(2) The feature of water transfer in North China is discontinuous supplement of water according to situation of water sh ortage,and is continuous supplement of water for the annual in North-West China.(3) A minimum risk ideal is suggested for decision of SNWTP.