Abstract: The current coefficient Ψ_s of correction includes many influencing factors.And numerical value of this coefficient varies widely.So the current method was improved from one coefficient to four coefficients in this paper.Three new coefficients of correction were considered to decrease composite ratio of coefficient Ψ_s and put forward three coefficients to modify calculating result.Foundation stiffness,lateral confinement assumption and soil turbulence were considered to get the value and method of the three coefficients. Consequently this study improves accuracy of numerical value of the coefficients.