This research focused on the development of numerical approximation procedure applied for resistance spot welding process which includes testing procedure to evaluate the tensile strength of a spot welded joint. The spot weld is modelled according to standardized dimension for tensile test with main material properties of Cu-sw as electrode and low carbon steel S235 as sheets with 1mm thickness. It is including electric conductivity, resistivity and heat transfer coefficient in solid body as well as contact interface. The FEM simulation is conducted using the process parameter of current 15,000A, force 5,000 N and different stages of time following the welding process and tensile test which is simulated after released both electrodes and material reaches the initial temperature with contact clamp velocity of 5mm/min. It is expected that the resistance spot welding process can be successfully simulated and producing result within acceptable range of errors.