Abstract: For the problems of high salinity and alkalescent clay soft ground improvement in south-east coastal land of China, this study analyzes the effects of salt concentration, acidity and alkalinity on cement-stabilized soil strength through experiment. The results show that the strength of cement soil is comparatively higher in alkalescent environment and the strength of cement soil is lower due to the obstruction of the pozzolanic reaction in acidic environment. With the salinity increasing, the electric double layer around soil grain surface becomes thin. The ion exchange are advantage to the reunite process. This process counteracts the strength decrease due to the acidity. Therefore, the salt concentration could influence the cement soil strength in acidity environment and not influence it in alkalinity environment.