The top spindle, end coupling and slipper metal are main components of the hot roll process and used for transmission of rotational power with heavy duty load. The top spindle connected with the motor and end coupling connected with the roller are combined with the slipper metal act as a bearing and joint. The contact surface between end coupling and slipper metal is occurred stress concentration, and life cycles of slipper metal is reduced. This study aims to minimize the mechanical problems which might happen in the production process. The derivation of load condition is conducted for hot rolling process under slipper metal combination types and operation situations. The structural analysis is performed by applying mechanical characteristics, combination type, and rotational boundary condition: top spindle, end coupling, slipper metal. Optimal design is performed for contact surface between end coupling and slipper metal. Interference analysis is studied to reduce the stress concentrations. The kinematics simulation is performed by applying the various combination type and dynamic boundary condition of the mill spindle assembly. The interference is not occurred on the top spindle and slipper metal, so actual driving of the hot mill spindle assembly can operate on the normal operation condition.