Using laboratory tests and scanning electron microscope, soft soil stabilised with cement in Nansha (China) was studied. The effects of cement ratio and curing period on the direct shear strength and the unconfined compressive strength of cement-stabilised soil were determined. The relationship between macro-mechanical properties and microstructure was also studied. The results show that the direct shear strength and the unconfined compressive strength of cement–soil increase with the increase of the cement ratio and the curing period. The growth rate of cement–soil strength decreases with the increase of the curing period. The change in the microstructure of cement–soil is the determinant of its macro-mechanical properties. This study was done to provide a reference for similar studies in the future and to help with engineering applications using cement–soil.