Abstract: Bending fretting fatigue tests of 30CrNiMo8 alloy steel were carried out at different bending loads, and the S-N curve of bending fretting fatigue was also built up, then the bending fretting fatigue characteristics and related laws of the steel were discussed. The results show that the S-N curve of the steel presented a shape of "C" curve, which was different from the curve of plain fatigue. With the increase of the bending fatigue loads, the fretting successively run in the partial slip regime (PSR), mixed regime (MR), and slip regime (SR), respectively. In the mixed regime, the cracks initiated most easily and the fatigue life was the lowest. The wear mechanisms in the fretting damage zones were mainly abrasive wear, oxidative wear and delamination. The propagation of the bending fretting fatigue cracks showed three stages, in the first stage, the crack extended obliquely at an angle and was controlled by the contact pressure, the crack turned in the second stage and was controlled by both contact stress and bending stress, and in the third stage, the crack propagated along vertical direction and was controlled by bending stress.