The high cycle fatigue strength of a cast iron cylinder head was evaluated according to engine bench test standard based on fatigue strength theory. The changing behaviors of temperature and stress with test conditions were identified and the influences of working load on each area of cylinder head were studied, which provided the load boundary for the life assessment model of cylinder head. The fatigue and damage analysis were further carried out according to fatigue theory based on the material correction. The analysis shows that the fatigue safety factor for each area of cylinder head except the cooling drilling hole is greater than 1, which is regarded to be safe.