Abstract: This article analyzed of the operation process and characteristics of combined trains in combined station of heavy haul railway, used simulation software to simulate the process of the trains in the microscopic aspect. Two simulation models were constructed separately, the trains in the first model had only one destination, and trains in the second had two destinations. Through analyzing the simulation data, it was found that the combination capacity and the utilization rate of arrival and departure track for combined trains in he second model were lower than the trains in the first model at the same yard. At the end, the article put forward relevant optimization measures to improve the combination capacity of combined yard.