Several experimentation parameters which for evaluating soil indexes were obtained based on the flat dilatometer test of calcareous soil in shallow water. The reasons of the calcareous soil density at surface layer in shallow water is bigger than that of deep-sited soil are not only the wave cycle dynamic loading

but also because calcareous soil were made of coral reef cementation material; and it has big pore and relax deposit material. So the flat dilatometer pressure is obviously different between surface layer calcareous soil and that of deep-sited soil. Also it has preferable correlativity between flat dilatometer test results and on-site standard penetration test results. Liquefaction estimation of calcareous soil in shallow water under different earthquake intensity can be obtained utilizing Seed simplified equation which is fit for calculating under-water mean dynamic stress ratio.