In this study, the effect of an additive with nano-montmorillonite brand on the process of self-healing on clay soil was considered. Laboratory tests include Atterberg limits and unpressurized compressive strength on the natural soil and soil samples contain different weight percentages of the additive. The results reveal that the addition of the additive up to 5% of the soil dry weight led to significant changes in the physical and mechanical properties of improved soil such as increasing plasticity index, increasing compressive strength and consequently, increasing the self-healing on clay soil. These changes are functions of the weight percent of the additive and the age of the samples. Moreover, laboratory results were investigated by SEM and FESEM images. Data was collected from uniaxial test and Scanning Electron Microscope images indicate that the maximum amount of self-healing occurred in the samples with 5% nano-clay on the sixtieth day after the initial failure.