In order to clarify the adaptability of heavy haul train to Shuohuang railway, a friction-type draft gear model is built by using “wedge-spring” simplification method. The comparison between simulated and measured data indicates that the draft gear model can effectively simulate the dynamic behavior of draft gear. Based on the empirical formula obtained by experimental data fitting, a train air brake model is established and verified. By dynamics simulation, the whole way coupler force of heavy haul train on Shuohuang Railway is analyzed. The train longitudinal dynamics on the ramp are also studied. The results indicate that several large coupler forces are generated, and the train is always on the concave ramp. It is concluded that the maximum coupler force on the variable ramp is bigger than that on the straight. Theoretical calculation results show that the variable ramp lead to the coupler force that also causes the longitudinal impact. The greater slope of the ramp is, the greater the coupler force will be. And the coupler pressure is also related to the position of the train. The simulation of the train brake on ramp with different slope combinations shows that, the longitudinal impact of the train brake results from both the asynchronous brake and the ramp. The coupler force on the variable ramp is the superposition of the two parts.