In order to carry on life determination on certain engine fan blade,high and low cycle fatigue tests were conducted on several specimens. The fatigue characteristic curve（ S-N curve,P-S-N curve） was obtained by statistical analysis.The results show that the S-N curve of this blade meet the law of quadratic function when the high cycle stress is greater than61. 51 MPa. In contrast,the high cycle fatigue is over the fatigue limit of general metal. The service life is associated with high cycle stress linearly. The disparity of service life is lower under high stress,while it is higher under low stress. In addition,the median life is about 2. 5 ,5 times of the safety lfe（ the survival rate is 99. 99%）.