Calcareous clay is a kind of hydraulic reclamation coral foundation soil, whose permeability is of great significance for the construction of coral reef island projects. Based on the GDSPERM automatic environmental geotechnical permeation test system, a series of consolidation and permeability combined tests of calcareous clay on one reef in the South China Sea have been carried out and the effects of void ratio, consolidation history, consolidation pressure and hydraulic gradient on the permeability of calcareous clay have been revealed. The nonlinear relationship between the void ratio and the permeability coefficient of the calcareous clay have been analyzed. Moreover, a series of permeability laws of calcareous clay have been summarized and an optimal nonlinear permeability model has been proposed.