Abstract: Deals with the experimental investigation on the reliability of gear-tooth fatigue for through hardening steel 35CrMo. The tests were canied out on a electro-mag-netic resonance fatigue test machine of type 1603 (U. K). Four loading stress levels (7 sample for each test) were conducted. Based on the test data, a R-S-N curve and related equation were fitted. Finally, the limiting bending fatigue strengh of the 35CrMo gear-tooth under different reliability have been evaluated.