A parametric model of flat head was established by using the conventional finite element software ANSYS.According to the results of elastic and elastic-plastic stress analysis, fatigue assessments were carried out respectively with the methods specified in ASME VIII-2 code and EN 13445 code to obtain the permissible numbers of cycles.On the basis of fatigue test data by Hinnant, the predicted fatigue life of the flat head was compared with the practical fatigue life.The results show that all the permissible numbers of cycles obtained from different assessment methods are less than the actual life of specimen, and the elastic stress analysis result based on ASME VIII-2 code is closest to the test value.