The objective of this study was to investigate the mechanical characteristics of implant-abutment interface design in a dental implant system,using nonlinear finite element analysis (FEA) method. This finite element simulation study was applied on three commonly used commercial dental implant systems:model I,the reduced-diameter 3i implant system (West Palm Beach,FL,USA) with a hex and a 12-point double internal hexagonal connection; model II,the Semados implant system (Bego,Bremen,Germany) with combination of a conical (45° taper) and internal hexagonal connection; and model III,the Brnemark implant system (Nobel Biocare,Gothenburg,Sweden) with external hexagonal connection. In simulation,a force of 170 N with 45° oblique to the longitudinal axis of the implant was loaded to the top surface of the abutment. It has been found from the strength and stiffness analysis that the 3i implant system has the lowest maximum von Mises stress,principal stress and displacement while the Brnemark implant system has the highest. It was concluded from our preliminary study using nonlinear FEA that the reduced-diameter 3i implant system with a hex and a 12-point double internal hexagonal connection had a better stress distribution,and produced a smaller displacement than the other two implant systems. The objective of this study was to investigate the mechanical characteristics of implant-abutment interface design in a dental implant system, using nonlinear finite element analysis (FEA) method. This finite element simulation study was applied on three commonly used commercial dental implant systems: model I, the reduced-diameter 3i implant system (West Palm Beach, FL, USA) with a hex and a 12-point double internal hexagonal connection; model II, the Semados implant system (Bego, Bremen, Germany) with combination of a conical (45 ° taper) and internal hexagonal connection; and model III, the Brnemark implant system (Nobel Biocare, Gothenburg, Sweden) with external hexagonal connection. In simulation, a force of 170 N with 45 ° oblique to the longitudinal axis of the has was been found from the strength and stiffness analysis that the 3i implant system has the top maximum von Mises stress, principal stress and displacement while the Br  It was concluded from our preliminary study using nonlinear FEA that the reduced-diameter 3i implant system with a hex and a 12-point double internal hexagonal connection had a better stress distribution, and produced a smaller displacement than the other two implant systems.