The　current　coefficient　Psi(s)　of　correction　includes　many　influencing　factors.　And　the　value　of　this　coefficient　varies　widely.　So　the　current　method　is　improved　from.　one　coefficient　to　four　coefficients　in　this　paper.　Three　new　coefficients　of　correction　are　considered　to　decrease　composite　ratio　of　coefficient　Psi(s)　and　three　coefficients　are　put　forward　to　modify　calculating　result.　Foundation　stiffness,　lateral　confinement　assumption　and　soil　turbulence　are　considered　to　get　the　value　and　calculation　method　of　three　coefficients.　Consequently,　this　study　improves　accuracy　of　calculation　result　greatly　by　actual　projects.