Abstract: Theoretical derivation complexity and numerical analysis complication are two main difficulties in Green’s function of vertical multi-layer soil.In order to overcome these difficulties,the symbolic equation method was presented as derivation method of Green’s function and the self-adapting high-accuracy complex image method was used to get numerical solution of Green’s function.Based on image transform and separation of variable method,the symbolic equation method was used as mechanized derivation method.The generalized closed form expression of Green’s function can be obtained without artificial derivation.By the intellectualized two-times-sampling method,numerical result of Green’s function was obtained.Then the matrix pencil method and the complex image method were utilized to approximate Green’s function.Because of the improvement on computational efficiency and precision,the self-adapting high-accuracy complex image method can be used as a substitution for Prony’s method or generalized pencil-of-function method.Checked by calculation example,these methods are accurate and effective for horizontal and vertical multi-layer soil.