In order to solve the problem of difficult theoretical modeling caused by complex threaded contact in the assembly and tightening process of bolted joint structure, a refined modeling method is proposed. Through the assembly torque model, the relationship between tightening torque and preload is obtained. According to the tensile and torsional equilibrium analysis of the bolt during the tightening process, the differential equations of tension and torsion of the bolt are acquired. Combined with the small deformation conditions and boundary conditions of the bolt and nut thread contact points during the tightening process, a complete stress distribution model is obtained. For the analytical model requirement in forward design, the analytical solution for bolt load and deformation distribution is obtained under the small deformation assumption and unchanged initial configuration, and a simplified analytical solution is further deduced. By simulating the stress distribution during tightening process, the screw load and displacement distribution curves under the specified torque are obtained. Comparison reveals that the numerical solution results are highly consistent with the analytical solution, providing a solid theoretical foundation for the forward design of fasteners.