Through the multibody dynamic simulation, the analysis model of the modalohr freight car of the DMT freight car was developed. By using the developed analysis model, the running dynamic characteristics was inquired through the dynamic analysis about the modalohr freight car. As the running speed and the primary suspension were increased, the lateral and vertical vibration accelerations of the car-body and the bogie were also increased. In case of the lateral vibration acceleration of the car-body, however, review should be considered since it can be influenced by the nonlinear characteristic of the primary suspension. The lateral and vertical vibration of the car-body were generated at the frequency of $2{sim}3;Hz$ and $7{sim}8;Hz$. And the lateral and vertical vibration of the bogie were generated at the frequency of $25{sim}35;Hz$ at the low speed section, $40{sim}50;Hz$ at the high speed section.