In the marine environment far from the mainland,there are some problems when placing traditionally vibrated concrete because it requires compaction by vibration in its forms.However,bad compaction qualities often cause durability problems.High fluidity concrete can properly flow into all corners of the mould and fill the framework without any or only a few additional compaction efforts,and hence is conducive to environmental protection and sustainable development.The slump flow and T500 of fresh high fluidity concrete were tested,and in the meanwhile the yield stress and plastic viscosity were measured by using viscometer.The results indicated that yield stress and plastic viscosity increase with water adding time,while slump flow declines with water adding time.The yield stress increases with silica fume content.The plastic viscosity declines at first and then increases.Besides,the yield stress was found to have a strong linear correlation with slump flow.The yield stress declines with slump flow according to this study.