Abstract: To improve the self-healing performance of micro cracks in cement-based materials, higher fatty acid salt was used to modify cement mortar to study the changes of mechanical properties, working properties and percolation properties of mortar under the action of higher fatty acid salt. The effect of higher fatty acid salt on the self-healing performance of micro cracks in cement mortar was discussed combined with the analysis of XRD and SEM-EDS of products at the crack. Results show that the addition of higher fatty acid salt can shorten the setting time of mortar to a certain extent, However, has little effect on the compressive flexural strength and fluidity of mortar. An appropriate amount of higher fatty acid salt with solid-liquid ratio can improve the compactness of cement mortar, increase the generation of calcium carbonate at matrix cracks, accelerate the self-healing effect of cracks, and improve the impermeability.