Following the technique proposed by Muki and Sternberg, the problem is decomposed into an extended soil mass and a fictitious pile characterized respectively by Young's modulus of the soil and that of the difference between the pile and soil. A Fredholm integral equation of the second kind is established which imposes the displacement compatibility condition. According to the generalized Hooke's law, the explicit solutions for the discontinuous point of the integral equation is derived, which improves the numerical accuracy and simplifies the calculation procedure. Based on the Mindlin's solution, the displacement influence function is derived which is simple. The results show that the pile-soil stiffness ratios have obvious influence on the position of the maximum bending moment for the pile under unit shear. With the increase of the pile stiffness, the position of the maximum bending moment of the pile is deeper.