Objective To investigate the stress distribution in the mandibula with oblique and vertical forces imposedrespectively in different positions of the occlusion surface of the posterior single tooth replacement. Method Thethree-dimensional(3-D) finite element method (FEM) was used to reconstruct the 3-D models of the mandibula, the firstinferior molar and the implant. The max EQV of the mandibula were calculated when oblique and vertical forces wereapplied to different positions of the occlusion surface of the implant. Result The max EQV of the mandibula were foundat the neck of the mandibula around the implant under both oblique andvertical load; The max EQV were significantlydifferent at different points with the same vertical load or with the same load at the different directions. Conclusion Themax EQV of the mandibula are at the neck of the mandibula around the implant and decrease progressively from the neckto the bottom under the oblique and vertical load; The largest max EQV was found at the neck of the mandibula around theimplant when the same load was applied to the distal locations; the various loading conditions play the important role thatcan influence the stress distribution at the neck of the mandibula around the implant.