Eco-protection slope is the sustainable development of highway construction. Forest roots can reinforce and anchor surface soil of slopes. The finite elements software ADINA is used to analyze mechanism of eco-protection slope through robinia pseudoacacia roots in different slope gradients. Tests are carried out to gain basic parameters through roots at field sites. During simulation

soil model is Mohr-Coulomb

and roots model is elastic bar. The results show that robinia pseudoacacia roots group in slope can make the upper layer of slope soil more stable by changing its stress and strain fields. As the slope gradient increases

the stress in the bottom of slope would increase and concentration area of strain would expand

while tensile stress would produce at the slope shoulder and its value would increase also; in this case

the effect of roots reinforcing slope would decrease.