When the expansive soil slope alternates between dry and wet,the slope soil will have obvious shrinkage-stretch and strength attenuation,which will easily lead to slope landslide and sliding accidents.Therefore,it is extremely important to obtain soil parameters quickly and accurately for treating and repairing expansive soil slopes.On the basis of the indoor soil test parameters of a waterway regulation engineering,the sensitivity analysis of soil parameters of the expansive soil slope is carried out by orthogonal test with the horizontal displacement measured at different depths by the actual layout of inclinometer tubes as the evaluation index.Then the soil parameter inversion model of the expansive soil slope is built by the least squares support vector machine（LS-SVM）,and the inversion model is verified.The soil parameters after inversion are obtained,and then the forward calculation of the most unfavorable conditions with obtained soil parameters after inversion for the treatment and restoration of the expansive soil slope is carried out to predict and analyze the deformation of the expansive soil slope.The results show that the inversion model based on the LS-SVM can realize the dynamic design of site construction and the prediction of slope deformation during the construction period.