Abstract: Because of axis line deflection and asymmetric load distribution of rotary kilns, the cracking of supporting shaft occurs frequently. Regulating operating axis is crucial to prevent shaft from cracking. By analyzing the shaft of supporting wheel, the relation between the axis line and fatigue strength of support system is derived. An optimization model is set up in which the regulating quantity of axis line is regarded as optimization variable and the difference between the maximum and the minimum safety coefficient is defined as objective function. An example is given to illustrate the present approach and some helpful conclusions are gained.