Generally rupture of steam generator tubes occurs accompanying significant plastic deformation. In this study, the burst pressure of a damaged steam generator tube is calculated from the plastic instability analysis using the finite element method. Two wear types, flat and circumferential types are considered. An equation for the burst pressure is proposed by using the concept of strength reduction factor and the Svensson equation. The analysis results are also compared with the experiment data from published references and they show a good agreement with the experiment data.