In order to fully find out water-physical characteristics of hard clay and improve the accuracy of geotechnical design in the west coast of Africa, water-physical properties of hard clay in the west coast of Cameroon are analyzed according to the results of surface geological survey, drilling, in-situ test and laboratory test, focusing specially on properties of swelling and shrinkage, collapse and softening. In hard clay, the analysis demonstrates that there is no swelling and shrinkage, slightly to non collapse, strong softening based on the status of unloading and facing water under multiple directions and unsoftening based on the status of surface unloading and facing water. The hard clay can be the bearing stratum of shallow foundation directly. According to the research, primarily waterphysical characteristics of hard clay are established in the west coast of Africa, reference data on the geotechnical design of hard clay are formed.