Transverse diaphyseal fracture is one of the most common fractures caused by accidents. The fracture treatment needs surgery to apply the fixations that matched the bone geometry. This paper aims to reverse engineering of a published bone plate and screw criteria into a three-dimensional (3D) model and analyze them using the finite element method (FEM) in several factors, the bone, the plate, the screw, the unification of plate and screw, and combination all components. This paper conducts two main activities of designing plate and screw based on literature for ulna bone implant and running the FEM to achieve the von Misses stress in the plate, screw, and bone by placing load and constrained area based on the actual use of the implant in the patient. The maximum number in von Misses stress are 5.01855 MPa for bone only, 0.00918 MPa for plate only, 193.304 MPa for screws only, 6.28160 MPa for the assembly screws and a plate, and 761.07 MPa for all unification. All simulation results meet the expectation that the bone analysis is less than the compressive strength of the ulnar bone. Moreover, when applied to the bone, the plate and screw analysis and the assembly also demonstrate a lower number than the yield strength of the properties of the Ti6Al4V materials. All this biomechanical assessment confirms that designs could withstand ulnar bone’s ultimate flexural load and pressure. The finite element analysis (FEA) on the proposed recreated dimension on ulnar plate and screw is expected to accelerate the rehabilitation process of radius ulnar fracture, particularly in the transverse diaphyseal fracture in ulna bone.