Abstract: Base on the mechanics theory and the analysis of disabled rods, the stress level of rod and its influential factories are analyzed in the paper. The results show that the stress level of rod is linear correlation with its ex-circle diameter, and enlarging the ex-circle diameter of rod is in favor of descends its stress level. At the same time, the anti-Fatigue life of rod is also predicted according to "S-N" curve and assembly program. The new-style rod innovatively adopts the thin-wall tubular structure, which is characteristic of the low stress and high anti broke resistance. So. it can achieve a high anti-fatigue life.