To　improve　the　accuracy　and　effectiveness　in　calculating　the　deformations　and　internal　forces　of　piles　with　large　exposure　lengths　under　horizontal　and　vertical　loads,　a　finite　difference　solution　was　established　based　on　the　composite　stiffness　principle　and　the　bi-parameter　method.　A　computation　program　was　compiled　by　means　of　MATLAB.　The　reliability　of　this　approach　was　verified　through　comparisons　with　the　measured　data　from　model　tests　or　the　calculated　results　of　an　engineering　example　with　the　existing　methods.　The　comparisons　showed　that　the　approach　was　more　convenient　and　faster　than　the　link　finite　element　method　based　on　the　same　principle.　It　was　also　showed　that,　for　piles　with　large　exposure　lengths　under　vertical　loads,　the　gravity　second-order　effect　must　not　be　ignored　and　the　vertical　loads　increased　not　only　the　bending　moments　of　piles　but　also　the　shear　forces.　The　influence　of　vertical　loads　on　shear　forces　was　not　reflected　in　the　current　methods,　which　tended　to　be　unsafe　and　should　be　noted　in　design　calculations　of　vertical　and　horizontal　bending　piles.　©　2016,　Science　Press.　All　right　reserved.