Abstract: In this paper，soft soil reinforced by slag and cement in Nansha ( Guangzhou) was studied． Through conventional soil test including direct shear test and unconfined compression test，reinforced soils mechanical property was researched and the correlation among its internal friction angle( IFA) ，cohesion，unconfined compressive strength( UCS) and mix ratio or curing age were studied． Scanning electron microscope observation( SEM) and X-ray diffraction technique( XRD) were used to study different microstructure characteristics and the mineral composition of different reinforced soil samples． The results showed that the IFA，cohesion and UCS of reinforced soil were raised increasing with the ratio of slag in curing agent，and cohesion was increased most obviously． The optimum was application of 60% slag，and the higher the ratio of slag be adopted，the faster the later strength of reinforced cement soil was raised． All of that were related to the microstructure and hydration products of reinforced soil．