Recently the use of the antiwashout underwater concrete with the antiwashout admixture is increased considerably. Antiwashout underwater concrete is quite different in concept from conventional underwater concrete. By mixing an antiwashout admixture with concrete, the viscosity of the concrete is increased and its resistance to segregation under the washing action of water is enhanced. The aim of this research is to evaluate the fundamental characteristics and permeability of antiwashout underwater concrete with fly ash and blast-furnace slag. Test Results of antiwashout underwater concrete with fly ash and blast-furnace slag fluence can provide its excellent fundamental characteristics and resistance of permeability.