Abstract: In this paper, the supporting bearings of the cross-flow fan rotor in the air conditioner are studied. Upon the mechanical analysis of the cross-flow fan rotor and the bearing, a calculation model is established for calculating the roller load of the supporting bearings in the cross-flow fan rotor. Upon the analysis of the structure of the rotor, the lumped mass discretization is carried out, and a numerical calculation model for the vibration performance of the special rotor is established. Together with the calculation method of the fatigue lifetime of the rolling bearing, a calculation model is established to calculate the fatigue lifetime of the supporting bearing with taking the rotor vibration into account. Through a numerical simulation for a specific example, it is found that the roller load and fatigue lifetime of the supporting bearings show strong dependence on the case whether the vibration has been taken into account or not. The influences of the rotor rotation speed, the length of the rotor and the number of fan blades on the roller load and fatigue lifetime of the bearings are studied with considering the vibration effects of the cross-flow fan rotor. These effects can be seen from the simulation results. With the increase in the rotation speed, the roller load of the bearing is increased, while the lifetime of the bearing is decreased. Similar influences are observed in the cases of increasing the length of the fan rotor and the number of fan blades.