Abstract: The surface erosion of expansive soil slope was a kind of common phenomena,so the slope surface protection was an important way to keep the slope stability.A series tests were performed on the water stability,saturated strength,erosion resistance of the expansive soils modified by the STW ecotypic soil stabilizer.The modified mechanism was analyzed using Scanning Electron Microscope(SEM).The field examination was carried out to explore the feasibility of STW stabilizer for the slope surface protection.It was indicated that the water stability,saturated strength,and erosion resistance of the modified expansive soil were obviously improved;the losses of soil and water from the slopes decreased greatly and the slope stability was enhanced.