Abstract: In order to acquire parameters in accordance with engineering practice,an experimental research on simulating the process of cyclic wetting and drying under loading condition for the undisturbed expansive soil obtained from Ningming(a city in southern Guangxi,China) was carried out,and the variation of deformation and strength were also observed.It was shown that the swelling-shrinkage deformation of expansive soils was not completely reversible.In certain range of variation of loading,during the same cycle,the total or relative ratio of the expansion and shrinkage decreased along with the increase of loads.Shear strength increased along with the increase of load,and decreased as the cycle number increase under the same load.However,the larger the pressure was,the attenuation rate of shear strength became smaller during cyclic wetting and drying.The effects of load in certain range were to restrain the swelling-shrinkage deformation and the attenuation of shear strength.